HUMBLE, Texas -

An armored car guard was shot when the bullets started flying during a robbery Monday morning outside the Chase Bank in Humble.

It happened at the Chase Bank at 19700 Eastex Freeway and Ranch Road just before 11 a.m. Monday.

For Kirk Filipp running errands quickly turned into a frantic attempt at dodging bullets in the busy Humble shopping center.  He was one of many terrified witnesses to a violent armored van heist.

"I was walking out of the cleaners and I was walking to my car to back out and then I heard gunshots," said Filipp.

Humble police say right across the parking lot at the Chase Bank, two guards were refilling an ATM with cash when three or four robbers ambushed them. Detectives say the suspects jumped out of a Dodge SUV and immediately started shooting. In defense, the guards pulled their own weapons and started firing back.

"My head went down and I looked up and all I could see was people running over by the money van," Filipp said.

Investigators say one of the guards suffered multiple gunshot wounds while his partner somehow escaped unharmed. With bullets flying from both sides, detectives say the robbers retreated back into the Dodge and fled the scene.

Officials said they may have switched vehicles a few blocks away. Investigators went to a nearby nursing home to examine an abandoned Charger.

In the aftermath, officers questioned the uninjured guard and combed through evidence; the ATM and shell casings, anything that could lead to the suspected robbers.

"They need to be locked up for a long time," Filipp said of the suspects.

Authorities said they are looking for three to four suspects. They are only described as black men who were wearing jeans and T-shirts.

Police tell us doctors were able to stop the injured guard's bleeding and get him into surgery. At last check, he was still in critical condition.

The investigation is ongoing.