The biggest fire in the history of New Westminster, B.C. has destroyed the city's abandoned Woodlands school for the mentally handicapped.

Fire crews from neighouring municipalities spent most of Wednesday battling a raging inforno that prompted the evacuation of adjacent buildings and could be seen from CTV's Chopper 9 helicopter as it hovered near the vacant mental institution. 

But they couldn't save the formerly government-run Woodlands Institution, which had been vacant since it was closed in 1996 after reports surfaced about decades-long patient abuse by its employees.

The building has been previously targeted by scavengers, who stole door knobs, piping and copper wires, police say.

Sgt. Ivan Chu of New Westminster Police said authorities don't know what caused the latest fire.

"We can't determine if it was squatters. Everyone can speculate, but all we know now is that this is the biggest fire to date,'' he said.

"It looks like they're just going to fight it from the outside and let it burn until at that time they drown out the fire.''

One of New Westminster's best known heritage buildings, Woodlands was built in 1878 to serve as a provincial asylum.