HERO SMILES: Nathanial Campbell, Keane Hall, and Zayed Rabbaney, all 17, put out a fire started by arsonists in the caretaker's shed at Spotswood College early yesterday morning.

Three Taranaki schoolboys have been hailed as heroes by their principal after dousing a deliberately lit blaze that threatened to engulf their school early yesterday.

But the fire, one of six arson attacks in New Plymouth late Saturday night and early yesterday has local fire chiefs worried.

The flurry of weekend arsons follows a fortnight of attacks on a Meade Place home in Bell Block, the old maternity hospital in Stratford and the toilet block at the Bowl of Brooklands.

About 1am yesterday, Spotswood College students Keane Hall, Nathanial Campbell and Zayed Rabbaney were taking a group of girls home from a party when they noticed the caretaker's shed on fire.

Zayed said the group were cutting through the school when one of them noticed the blaze.

"Keane stopped and said, 'is our school on fire?' You could see embers and smoke flying in the air," the 17-year-old said.

The trio ran to the shed, before calling the fire brigade. "We smashed one of the classroom windows and got the hose so we could put it out," Nathanial said.

"Another guy came running over and helped too."

There were diesel cans within metres of the fire. "I was scared it was going to blow up," Keane said. "It was so hot."

As the trio were putting out the fire two guys popped out from a pathway behind the shed.

"They came out and said they didn't do it, but you could just tell, there was something dodgy about it," Keane said.

Police have charged a 15-year-old and 19-year-old with arson.

It's alleged the pair also set fire to a skip bin near the Hunting and Fishing store at Port Taranaki and a wheelie bin on Whiteley St, Sergeant Kim Vollmer said. They will appear in court today.

Spotswood College principal Mark Bowden couldn't praise the three young men enough yesterday, saying he was lucky to still have a school.

Mr Bowden said the fire was just seconds away from turning nasty. "It could have been significantly worse.

"And with the southeasterly blowing it could have spread to the gymnasium," he said.

The spate of arson attacks in the past two weeks were a frustration for firefighters, Taranaki area manager Pat Fitzell said.

Mr Fitzell said it was not only a waste of time and money, but it did it put people's lives in danger.

"They (arsonists) have lost their brains. They have no thought for other people's safety," Mr Fitzell said. "You're putting firefighter lives at risk when you send them into a burning building."

Mr Fitzell said arson was a serious crime and there needed to be a stronger deterrent.

"Sometimes you would like to get hold of them, lock them up and throw away the key," he said.

Arsonists are taking firefighters away from what they were really there for, he said.

"The whole time we're chasing these silly buggers around we could be needed elsewhere in a hurry."