CHARLOTTETOWN, Prince Edward Island — An explosion rocked one of Canada’s most historic buildings Thursday, the Prince Edward Island legislature, injuring one man and sending a shower of glass over lawmakers.

Glass and debris were hurled at least three blocks by the midafternoon blast, which took place when the 32-seat legislature was in session.

Fearing another attack, lawmakers crawled out of the building on their hands and knees, said Ross Young, a member of the legislature.

Investigators believe the explosion was caused by a bomb planted under a wooden wheelchair ramp.