New Zealanders have described the scenes after explosions at the finish line of the Boston Marathon as "chaotic" which have claimed the lives of at least two people and injured many more.
Victoria University academic Roger Robinson and his wife, renowned marathon runner Kathrine Switzer, were forced into lockdown in their Boston hotel close to where the explosions happened.
Ms Switzer, who was famously the first woman to enter and run the Boston Marathon in 1967, was on the photo bridge involved in television coverage of the event shortly before the explosions.
"I had left the area just before the explosion and am now in my hotel with my husband. Our hotel and the area is in lockdown,'' she posted on Facebook.
"This is a sad, sad day.
"Thank you for your concern. Please hold everyone here in your thoughts and prayers.''
Wairarapa accountant Graeme Tindall was only 1.6km from the finish line of his 86th marathon when the explosions ended the race.
Mr Tindall, an accountant at Forest Enterprises, has been in touch with family and friends in New Zealand to say he is safe, his boss Steve Wilton said.
"He was very close [to the finish line] at the time it occurred but he was at a safe distance. He was running slower than he expected, so that was a blessing with hindsight,'' Mr Wilton said.
"His biggest worry was to be able to get back to his hotel [which was in lock down after the explosions].
"We've had confirmation that he's been allowed in.''
Mr Wilton said Mr Tindall was awaiting confirmation that he would be able to fly out to Seattle tomorrow.
Former University of Otago graduates and friends Nicolas Menzies, who is studying at Harvard University in Boston, and Dr Xaviour Walker had both registered to run the marathon but chose not to compete.
Mr Menzies' uncle, Richard Bright of Auckland, finished the race about 10 minutes before the first explosions.
Speaking from his nephew's house in Boston, Mr Bright said he never heard the explosion over the noise of the crowd, which had started to build as more runners finished the race.
"There were some frantic phone calls [to family and friends in New Zealand],'' Mr Bright said.
"Everyone is really in shock. It strikes to the heart of American society.''
Mr Bright said he almost slowed down to walk the last portion of the marathon because he had another race coming up in two weeks.
"I decided I wasn't going to bust myself so why wouldn't I walk it when I was stuffed. Then I thought it was jolly cold out there ... I thought the pain of this cold is worse than the pain of running so I better pick up the pace and finish,'' Mr Bright said.
"If it weren't for that I would have been right into it [the explosion].
"It's like gee, it could well have been [a different story].''
Olympian Sir John Walker said the terror attack was a black day for sport.
"People were going out for a bit of fun, enjoying it and supporting their fellow men. What sort of mindset do you have to do something like that?''
He said the terror attack would "put the scare up'' other marathons and sporting events, if not in reality then in perception.
The Ministry of Foreign Affairs and Trade says there were at least 45 New Zealanders registered to run the marathon and there have been no reports of New Zealand runners or spectators being injured.
Mfat has offered assistance to anyone who cannot reach family or friends in Boston. Anyone with concerns should call 04 439 8000 and ask to speak to a consular adviser.
"The embassy in Washington is monitoring the situation closely and liaising with local authorities to determine if any New Zealanders are in need of assistance," a spokesman for Mfat said.
Prime Minister John Key said New Zealand's consul-general in Boston Simon Leeming has been working with two New Zealanders who were close to the explosion.
He said they were not injured but had contacted the embassy.
Mr Key said there had been no news of other New Zealanders injured in the explosions.
He said there had only been five calls to the embassy from New Zealanders.
"It's a very frightening and serious situation; our hearts go out to those who have lost loved ones, or who have been injured."
Mr Key said information that had come in about the explosions had been "relatively sketchy" and it was unclear what the cause had been.
He said the Government was working with officials in New York and Boston.
New Zealand runner Maxim Lukashov had been separated from his girlfriend after both were put into lockdown before they could finish the marathon.
Speaking from his hotel room in Boston, Mr Lukashov told APNZ he was about 500m from the initial explosion and saw smoke before the race was called off.
He said his girlfriend, who was about 10km behind him, had been told to stay in a church as authorities closed down areas of the city.
"It was pretty chaotic out there, people did not know what was happening," Mr Lukashov said.
"My girlfriend, she's stuck in a church because she was [further] behind. I'm not sure when she's coming back but she emailed [to say she was safe]."
Mr Lukashov said the only people on the streets around his hotel, which is close to where the explosions happened, were police officers directing traffic.
"It's pretty frightening," he said.
"I'm looking outside and there's about five cops at each intersection directing traffic, [which is] all the police and ambulance cars.
"I've never seen so many police and ambulances."
Wellington runner Andrew Wharton, who competed in the marathon, was one of several Kiwis near the explosions.
He was evacuated with his wife from their hotel close to where the first explosion happened.
He told Radio New Zealand he felt it from their fifth-floor hotel room and looked down to see "debris everywhere".
"It was pretty loud, it shook the hotel, and it was right there. As we were evacuated we walked through trails and pools of blood," Mr Wharton said.
"We just didn't look back, we just got out of there.
"The shops to the right of the hotel were [damaged]. When I looked down I could see debris everywhere.
"It was obviously where spectators were standing right on the finish line so there were obviously barricades down and it was just pretty chaotic.''
Former New Zealand politician Laila Harre told APNZ she had just finished the marathon and was about 200m away from one of the explosions.
"I was in the area where you get drinks and blankets and pick up your gear.
"It was very loud, but people didn't react in a panicked way at all.
"It's a sound I haven't heard before."
She said she was in shock. APNZ spoke to her as she was walking away from the downtown area.
Ms Harre said the crowds around the marathon track were "unbelievable" with people lining the streets around the race track.
New Zealand Olympians Nick Willis and Kim Smith took part in an earlier shorter race and had left Boston before the explosions, Radio New Zealand reported.
Expat New Zealander Penelope Strong, who lives about 1.6km from the finish line of the marathon, heard the explosions from her house.
She said she first heard about the incident via text messages from friends in New Zealand.
"All we heard was a loud bang and then a million police cars, undercover cops, regular cops just streaking in one direction," Ms Strong told Radio New Zealand.
"It's a big city so you hear loud noises all the time so it didn't really register for us until people started mentioning it."
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