Two people police are calling “good Samaritans” may have thwarted an attempted daytime robbery of an armored car in Prince George’s County on Wednesday by tailing the suspected thieves until officers arrived to investigate, authorities said.

Within hours of the reported robbery, police arrested all four suspects they believe were involved and retrieved the money bag and guns taken from the two guards driving the armored vehicle, police said.

The incident began shortly before 11 a.m., according to Prince George’s police spokesman William Alexander. An armored car was going to pick up cash from a Checkers Drive In on the 4800 block of Allentown Road, just outside the Capital Beltway. Three men confronted two guards conducting the cash pickup, getting away with a money bag and two guns, Alexander said. The suspects got into a green Jeep and tried to escape.

But two witnesses, one of whom is reported to be a former Marine, got into a red pickup truck and followed the green Jeep, Alexander said. The men in the green Jeep shot at the red car.

Read more: Washington Post