PHILADELPHIA — A robber shot and killed two armored car guards servicing an automated teller machine outside a bank early today, authorities said. Several schools were locked down amid a massive manhunt for the gunman.

One man fatally shot the Loomis armored car guards shortly after 8 a.m. outside a Wachovia bank in Northeast Philadelphia, Police Commissioner Sylvester Johnson said. Police initially said they were looking for four suspects, but Mr. Johnson said it appeared there was only one robber.

The gunman shot one guard as he was removing cash from the ATM and then ran around to the other side of the armored car and shot the second guard, Mr. Johnson said.

A Loomis spokesman, Mark Clark, said a third guard, the driver, was grazed by shattered glass as the robbers tried to shoot through the armored car. He was hospitalized in good condition.

Police said the suspect fled in a black sedan. A short time later, police recovered a black duffel bag filled with cash behind the Turf Club, an off-track betting parlor directly behind the bank, a police spokesman, Officer Raul Malveiro, said. Police did not have details on how it got there.

Investigators were trying to determine whether the guards, who were armed, exchanged fire with the robber, Mr. Malveiro said.

Entrances to and from the mall complex where the bank is located were shut down and police were stopping motorists leaving the area.

Several schools in the area were placed under lockdown amid a massive manhunt in the area. The mall also was shut down.

Mr. Johnson said investigators were reviewing surveillance video from the bank, which is at a busy intersection of shops and other businesses.