People, including children, are trapped after the blast in a residential area in Baltimore, fire officials say

The explosion left several people, including children, trapped, a local firefighters union said on Twitter. Overhead video of the scene showed first responders searching through the rubble.

People gather outside an explosion site in Baltimore on Monday.

Three people have been rescued by firefighters, the Baltimore Firefighters IAFF Local 734 said, and the Baltimore Special Rescue Operations Team has begun search and rescue operations.

Baltimore City medical units and Baltimore County Fire Department units also have been called to the scene.

Firefighters at the scene of where homes were destroyed.

James E. Bentley, the Baltimore City Mayor’s spokesman, told CNN he is aware of the reports and was headed into a meeting about the situation.

This is a developing story.