An explosion rocked a residential area in northwest Baltimore on Monday morning, destroying three homes in what city fire officials are calling “a major gas explosion.” One woman was pronounced dead at the scene and at least two more are believed to be trapped in the wreckage. Baltimore County fire units were called to scene.

Two others were taken from the scene in critical condition. One was taken to the University of Maryland’s Cowley Shock Trauma Center, while the other was taken to Sinai Hospital.

“We are closely monitoring the situation in northwest Baltimore following this morning’s horrific explosion,” Maryland Gov. Larry Hogan said in a tweet. “We have reached out to offer our full support to the ongoing response and recovery efforts, and are deeply grateful to the first responders on the scene.”

While the exact cause of the blast has not been confirmed by officials, gas lines in the area have been shut down as a precaution. Electrical wires, however, remain active.

According to local reporter David Collins, many of the injured residents at the scene appear to be senior citizens.

A spokesperson for Mayor Bernard C. Young confirmed the he was aware of the situation and was heading to a briefing on the matter.

Baltimore An aerial view of the skyline of the ninth best city for jobs, Baltimore, Maryland, Dec. 1, 2016. Photo: Getty Images