Excuse me sir, your pants are on fire

A Havelock North principal was eating a sandwich one minute and in the pool the next after his shorts "spontaneously ignited".

Te Mata School principal Michael Bain was operating the starting gun at his school's swimming sports event yesterday, something he's done for years.

He had stopped for a snack between the races held at Havelock North Village Pool when he realised his shorts were on fire.

The starting gun caps in his pocket had burst into flames.

"They just spontaneously ignited. Basically the starting gun caps self-ignited, which set fire to my shorts, which caused me to jump into the swimming pool. I was just standing there having a sandwich, and then 'boom'. It was just one of those freak, out-of-the-blue accidents."

He jumped into the water fully clothed to extinguish the fire, much to the confusion of the primary school pupils at the event.

"I think the novelty of me standing in the pool was more of interest to them."

He was taken to Hawke's Bay Hospital with "a large burnt patch" on his leg, and later discharged.

Mr Bain would be taking time out from his duties during the next couple of days, as he nursed his burn wound.

"I'll be getting plenty of hydration and keeping it moist."

He was also saddened to lose a pair of shorts.

"My shorts are not quite so good, which is quite depressing, because it was only the second time I'd worn them."

It had not yet been determined how the caps ignited.

Napier Fire Service senior station officer Jamie Nichol, when told about the incident, said he'd never encountered anything like it.

"I've been in the Fire Service for 24 years and I've never come across anything like this - it's very unusual. He's one unlucky man."