As authorities investigate the cause of a deadly explosion and apartment fire in an apartment complex outside the nation's capital, they are looking into reports that residents smelled natural gas before the blast.

Two people were killed, others are missing and more than 30 were taken to hospitals for treatment. Police did not release the identities of the dead.

Firefighters used ladders to rescue people from upper floors, and residents tossed children from balconies to safety below.

Police said an unknown number of residents remain unaccounted for.

The explosion late Wednesday night sent debris hundreds of feet, and people more than a mile away reported the blast was strong enough to shake their homes.

County officials were trying to help worried family members account for missing loved ones.