LITCHFIELD PARK, Ariz. (AP) _ A B-1B bomber made an emergency landing without incident Tuesday afternoon at Luke Air Force Base west of Phoenix because of electrical problems on a training flight, officials said.

Base spokesman Bill McKenzie said the aircraft was based at Ellsworth AFB outside Rapid City, S.D. However, he said he did not know if the flight originated there.

Built in 1941 to train fighter pilots, Luke is a Tactical Air Command base with no bomber squadrons. However, McKenzie said the B-1 had no problem setting down on one of two 10,000-foot-long runways about 12:50 p.m.

He said officials did not know whether weapons were aboard, or what type they might be. The supersonic, four-jet plane has a 137-foot wingspan and is capable of ''unrefueled, intercontinental flights,'' said Lt. Col Chris Weber, Luke's public information officer.

He said the plane has a four-man crew.

McKenzie said the plane landed because of an in-flight emergency, which can range from an instrument-panel signal to structural damage.

''It could be a multitude of things, and of course we don't know what the malfunction was right at this time,'' McKenzie said.

Maricopa County sheriff's deputies began closing streets east of the base about 30 minutes before the landing, but Air Force officials said they did not ask for such action.