A major explosion tore through a Baltimore neighborhood on Monday, leveling several houses, trapping at least five people and critically injuring three, firefighters said.

Images on WBFF television showed a section of row houses leveled with rubble strewn about.

Three patients, all in critical condition, were rescued by firefighters, the Baltimore Firefighters IAFF Local 734 posted on Twitter.

"Several houses exploded. At least 5 people trapped, some children. A Collapse Response and Second Alarm has been called," the union said on Twitter.

The union tweeted photos of rescue workers climbing over a pile of debris.