Fountain Valley police and Southern California Edison responded Monday to an underground explosion that caused the loss of power to thousands of customers.

The explosion, or what Sgt. Kurt Ulrich called a "significant boom," occurred around 8 p.m. at Brookhurst Street and Edinger Avenue. No one was injured.

Ulrich said police shut down the southbound lanes of Brookhurst for three hours and reopened them at 11:28 p.m.

Edison spokesman David Song said about 3,000 customers were affected by the failure of underground electrical equipment. Preliminary reports don't state if it was a transformer, but Song said something in the power company's subsurface vault malfunctioned.

Song added that SCE had power restored by 3:18 a.m. Tuesday.

"It doesn't happen frequently, but it does happen," he said. "With underground equipment, it does take a little longer to assess ... and fix the problem."

— Anthony Clark Carpio

Twitter: @Acocarpio