Fiery freight train crash in Md.

Smoke billows from a train derailment that caused a major explosion in the Rosedale neighborhood in Baltimore, Md., May 28, 2013.

Residents in nearby neighborhoods were advised to voluntarily evacuate.

Read more: Feds prob cause of freight train collision

A video still shows an explosion outside Baltimore, May 28, 2013.

Baltimore County fire officials say a freight train derailed in a Baltimore suburb on Tuesday and an explosion was heard in the area.

A fire burns at the site of a CSX freight train derailment, May 28, 2013, in Rosedale, Md., where fire officials say a train crashed into a trash truck, causing an explosion that rattled homes at least a half-mile away and collapsed nearby buildings, setting them on fire.

A fire burns at the site of the CSX freight train derailment, May 28, 2013.

Mark Paugh carries his 15-month-old son Ryan as they watch smoke from a train derailment in Rosedale, Md., May 28, 2013.

Windows of a nearby business are blown out from a train derailment that caused a major explosion in the Rosedale neighborhood of Baltimore, May 28, 2013.

A worker walks by as smoke billows from a train derailment that caused a major explosion in the Rosedale neighborhood of Baltimore, May 28, 2013.

A fire burns at the site of the Baltimore freight train derailment, May 28, 2013.

The explosion from the train derailment in Baltimore, May, 28, 2013.

Smoke billows from a train derailment that caused a major explosion in the Rosedale neighborhood of Baltimore, May 28, 2013.

As smoke fills the sky, passersby try to get a better look at a train derailment that caused a major explosion in the Rosedale neighborhood of Baltimore, May 28, 2013.

A Foam Unit tries to control fire from the Baltimore train derailment that caused a major explosion, May 28, 2013.

Workers gather near the sight of the train derailment that caused a major explosion in Baltimore, May 28, 2013.

Windows of a nearby business were blown out by the explosion after a train derailment in Baltimore, May 28, 2013.

A helicopter circles as smoke billows from a train derailment that caused a major explosion in the Rosedale neighborhood of Baltimore, May 28, 2013.

A fire burns at the site of the freight train derailment in Baltimore, May 28, 2013.