(Reuters) - A third body has been found in the rubble from an explosion and fire this week in the Washington suburb of Silver Spring, Maryland, and others remained missing as authorities continued to investigate on Saturday, according to police statements.

An explosion and a fire ripped through an apartment complex in Silver Spring on Wednesday night. Police have not yet identified the three victims, Montgomery County Police Department said in a statement on their website posted Friday.

Search and recovery efforts were continuing over the weekend for several residents still missing. It remained unclear how many people were missing, though authorities earlier this week said some five to seven residents were unaccounted for.

The cause of the explosion remained unclear.

Federal agents from the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) continued to help local fire investigators, Montgomery County Police said on Twitter on Saturday.

Washington Gas, a unit of WGL Holdings Inc, which provided service to the complex, said in a statement it was helping in the investigation.

The blast and fire Wednesday in the four-story complex injured 34 people, including three firefighters.

Local officials said residents reported smelling gas just before the explosion, which was felt over a mile (1.6 km) away and tossed debris as far as 300 feet (90 meters).

The bodies of all three victims were transported to the Chief Medical Examiner's office in Baltimore for autopsy and possible identification, the police department said on its website.

About 160 firefighters battled the blaze, which was brought under control after about two hours. Television footage showed flames and smoke pouring from the building as firefighters rescued a man from an upstairs apartment window.

(Reporting by Chris Prentice in New York; Editing by David Gregorio)