Durham, N.C. — A robbery involving an armored truck outside a Durham bank late Tuesday morning did not appear to be a random act, investigators said.

"I would say this was definitely planned," Durham police Maj. Lee Russ said. "I don't think it was a crime of opportunity."

The robbery unfolded shortly before noon outside the Bank of America on Hope Valley Road in the Woodcroft area, police said.

A security guard for Dunbar Armored was walking out of the bank with an undisclosed amount of money when a man came out of a car parked between the bank and the armored truck and started shooting.

"It was an ambush," Russ said. "It happened extremely quickly."

A bullet hit the armored truck. A stray bullet hit a car driving by.

No one was shot, but one of the security guards with the armored truck injured his hand, police said. He was treated at the scene.

In an attempt to find cover, he fell down, got up and ran off but left the money on the ground. The assailant grabbed it. Police said the guards did not return fire.

The assailants fled from the scene with an undisclosed amount of money, authorities said. They were last seen wearing either dark blue or black clothing, and one or both were wearing masks at the time, according to initial reports from Durham Police dispatch.

They were last seen traveling northbound on Hope Valley Road in an older gray Ford Taurus. They are considered armed and dangerous, authorities said.