Two Wal-Mart stores in Long Beach received back-to-back bomb threats Thursday morning, prompting evacuations at both locations, according to authorities.

Police said they learned of the first threat around 8:45 a.m. when employees at a store in the 3700 block of South Street contacted them.

The store had received “a suspicious letter regarding an explosive device that had been placed in the store,” Long Beach police spokesman Sgt. Brad Johnson said.

Around 11:30 a.m., a second Wal-Mart store — this one in the Long Beach Towne Center — also reported receiving a threatening letter about explosives, police said.

That store, in the 7200 block of Carson Street, was also evacuated, Johnson said.

Police swept through both locations with K-9s without finding anything suspicious, according to Johnson.

The Wal-Mart on South Street reopened early Thursday afternoon and the location in the Towne Center reopened a few hours later, police said.

No further details were immediately available.