SAN FRANCISCO, July 13 (Xinhua) -- A 69-year-old man was shot and killed by four police officers when attacking a Tacoma immigration jail in the U.S. northwest state of Washington early Saturday morning, the authorities said.

The Tacoma Police Department said the man, identified as Willem Van Spronsen of Vashon Island, armed with a rifle threw incendiary devices at the Northwest Detention Center, a U.S. Department of Homeland Security detention facility that holds immigrants in Washington.

Police spokesman Loretta Cool said Van Spronsen ignited a car and tried to explode a propane tank before he was fatally shot by four police officers.

No officers were injured.

The shooting took place about six hours after a peaceful rally in front of the detention center.

The motive for Van Spronsen's actions was not known, Cool said.

According to authorities, the police are working with the Federal Bureau of Investigation and the Department of Homeland Security to conduct further investigation.