A major explosion in a Baltimore neighborhood has killed a woman and severely injured seven others, with emergency responders continued to drug through the rubble Monday night.

Blair Adams, a spokesperson, said, “Three homes were reduced to rubble.”

Earlier, Adams said six people were hospitalized in serious condition. However, on Monday night, the department said the seven people were injured but did not give their conditions.

Officials have been investigating the cause of the explosion, with crews searching for people who might be trapped inside. Some authorities said they thought it was a gas explosion.

In a statement provided by Tasha Jamerson, Strategic Communications Manager and Spokesperson at the Baltimore Gas and Electric Co. (BGE), said no gas reading was found in any of the buildings, and no leaks were found on the gas main.

The BGE also said there were no gas odors reported before the explosion.

The statement read, “Our crews are continuing to inspect area gas mains and services for safety and will make any necessary repairs if any issues are found.”

On Monday morning, Adams said, “You have homes that were pretty much crumbled … a ton of debris on the ground, so we’re pulling and trying to comb through to see if we can find any additional occupants.”

Maryland Governor Larry Hogan said the state Fire Marshal, the Maryland Emergency Management Agency, and the Maryland Public Service Commission are all helping with the blast recovery.

He said, “So far, we know that the explosion has taken one life. Our prayers are with the victims and all those affected by this tragedy.”:

Last August, a gas explosion destroyed a building in a shopping center in Columbia, Maryland.

Last September, the Baltimore Sun reported that natural gas has been leaking out of old pipes increasingly in recent years.

The Sun reported that at the current rate, efforts by BGE to replace the pipes would take at least two decades.

Jamerson said BGE has undertaken an initiative to replace the worst old pipes. She said, “The pipes in this area were installed in the 1960s,” adding they were inspected a little more than a year ago and no leaks were discovered then. BGE, which is the nation’s oldest gas company, said it currently provides gas to over 680,000 customers and has over 7,600 miles of natural gas pipeline.