BALTIMORE (AP) _ Fire broke out in a chemical warehouse Tuesday, prompting the evacuation of a one-block area.

Whether anyone was injured or was even in the warehouse when the fire broke was not immediately known, fire spokesman Hector Torres said.

In addition to the evacuation for those closest to the fire, residents within five blocks of the three-story warehouse were told to stay indoors with the windows closed.

For the second time in less than two weeks, the city's civil defense siren was sounded to warn residents. Two weeks ago, a freight car derailment, acid spill and fire prompted the sounding of the siren for an emergency for the first time in a half-century.

The fire is in a residential area about three-quarters of a mile northeast of downtown.