The Detroit-based utility told the Free Press on Tuesday it would have taken a "significant amount" of gas to set off such a powerful blast, and that a leak should have been detectable by its odor, which is added and often described as a "rotten egg" smell.

A gas leak caused Monday's explosion and fire on Littlefield Street, Detroit Fire Investigation Division reports.

Investigators have determined a gas leak caused an explosion early Monday morning at an apartment building on the city's east side that injured 13 people, three of whom remained in critical condition on Tuesday.

About a dozen people have been injured, including six children, following an apparent explosion and fire Monday morning at a 2-story apartment building in Detroit. The explosion was reported about 4 a.

A demolition company will tear down the structure after investigators have finished because it is not safe to be occupied.

A blast so powerful that it blew out windows, ripped away bricks from a westside building wall, and injured a dozen people, including six children, is under investigation early Monday, as demolition crews try to stabilize the structure.