The tragedy at Dreamworld, where four people have died, is the second major incident on a ride at the Queensland theme park in just six months. Two men and two women died on the Thunder River Rapids ride at the Gold Coast's biggest theme park on Tuesday afternoon. In April, a man almost died on the park's 35-year-old Rocky Hollow Log Ride which led to the attraction being shut down. Meanwhile, a Dreamworld visitor wrote to the theme park just weeks ago complaining of safety at the park warning, "someone will get killed one day". The concerns were dismissed by Dreamworld. LISTEN: Australian correspondent Donna Demaio speaks to Rachel Smalley about the Dreamworld tragedy The park's Facebook page has also been inundated with posts from previous visitors to the theme park complaining of incidents they experienced. A man in his 30s fell off the log ride attraction and almost drowned in the April accident. The log flume, which operates on a similar conveyor-belt system to the Thunder River Rapids ride involved in today's incident, was reopened two days later after checks to the mechanism by Worksafe Queensland, according to the Gold Coast Bulletin. Dreamworld CEO Craig Davidson said at the time his thoughts were with the man injured and he wished him a speedy recovery. Mr Davidson said guest safety was Dreamworld's number one priority. The Facebook page of the Gold Coast destination has also been flooded with customers concerned about the safety of rides. Tasneem Seedat complained that the rides, some of which are more than three decades, were "out of date". "I injured myself on the way down from the giant drop because of your old school repairs and upgrades. Wipe-out and a few others need replacing." Ms Seedat also said safety standards were concerning. "For all of your rides there is only 1 or at max 2 people operating it and checking harnesses." In early October, Patrick Boundy said "The Tower of Terror ride didn't brake properly and we had to wait for engineers to come and get us off the ride." Dreamworld thanked Mr Boundy for getting in touch and encouraged him to contact their customer service centre. Just days ago Gold Coast mum Tracy Christensen posted a lengthy complaint to the park's Facebook page raising her safety concerns. On October 10, Ms Christensen wrote her family was repeatedly told to leave rides due to "operational issues". However, her worries were magnified when her children went on The Claw ride. "The kids get off The Claw and said one of their belt buckles come undone right up in the air. I told the attendants - they didn't listen. I went and told the manager, and he said he will call someone to go have a look, yet they continued to let people on the ride and keep operating," she wrote. "I went back to the manager and questioned it and he tells me that the belt buckle is an added safety feature Dreamworld added to the seats, so if they come undone they are still safe. "There must have been a reason they added those belt buckles or they wouldn't have bothered." Ms Christensen said the log ride, where the incident occurred in April, was also broken. "Having five rides with operational issues is not good enough. Someone will get seriously injured or killed one day!" Dreamworld replied that the rides were not broken, but "resetting" themselves. "Our rides are computerised and sometimes they need a reset, just like your computer or your own phone might," they replied. "The rides are not broken, they are acting as they are designed to do for safety." the reply said. "Tracey, the lap belt on The Claw is to help have riders in the position required for the harness to come down, and is not in anyway related to keeping you in place. We check these if they come open because it can scare a rider, even if they are completely safe." Ms Christensen was not convinced. "The Tower of Terror went half way up then rolled back in the cave thing then rolled back out. My partner saw the whole thing. You can't tell me that's a 'reset' problem? It came undone! It was dangling between his legs!"