The New Orleans Police Department has opened an internal investigation into the department’s apparent mishandling of a bomb threat called in to dispatchers Tuesday by a man who said he had placed explosives in an elevator shaft at the LSU Health Sciences Center.

The threat turned out to be a hoax, but because of an apparent lapse in protocol, it took almost seven hours for the building to be evacuated.

The caller made his threat about 6 a.m., saying he was angry about the hiring of immigrants. Officers apparently decided there was no real threat, although the basis for their determination is unclear.

“That’s what’s under disciplinary investigation,” said Tyler Gamble, a spokesman for the NOPD.

The building, at 2000 Tulane Ave., eventually was evacuated and searched about 1:30 p.m.

Gamble said normal protocol when a bomb threat is received is for officers to contact the building supervisor, who gives police authorization to evacuate and sweep the building.

In Tuesday’s incident, that didn’t happen until the early afternoon.

“The problem is that they (officers) made the determination (that there was no threat) without getting with the supervisor, going through the building and conducting an evacuation,” Gamble said. “Protocol wasn’t followed, and that’s what’s under disciplinary investigation.”

The officers being investigated are Sgts. Henry Burke and Ricci Fayard and Officers Damian Cornia and Travis Stokes, Gamble said.