BALTIMORE (AP) — The company that operates Baltimore’s underground steam pipe network says abnormal thinning of a pipe wall caused an explosion on a downtown street.

The explosion on June 20 sent water gushing several stories high, buckled the street, shattered windows on cars and buildings, and injured five people.

Veolia North America said in a news release Wednesday that its analysis showed that abnormal pipe wall thinning was found at the break.

The company says the event was “extremely rare.” Veolia says the cast iron pipe has been replaced with ductile carbon steel.