RCMP vehicles blocked an intersection in north Burnaby on Wednesday after unexploded bombs were found in a residential neighbourhood. (CBC)

A high school and nearby homes were evacuated and roads were shut down in Burnaby, B.C., late Wednesday after two unexploded mortar shells were found in the area.

The evacuations occurred near Alpha Secondary School in the area of Willingdon Avenue and Parker Street, in north Burnaby.

The devices were found in an alley about half a block from the school.

It's not known how long the bombs had been there. The shells are a component of a portable military weapon that lobs them at targets up to several hundred metres away.

Firefighters took photos of the shells and emailed them to military officials at the Department of Defence, who identified them as Canadian Forces munitions. The officials were making arrangements to retrieve them.

Road closures ran from Willingdon Avenue to Gamma Avenue and from Parker Street to Napier Street.

It's expected that people would be allowed to return to their homes for the night, and that the school would be open for classes Thursday.