Deputy Smith was on patrol in his police car when he heard a report over the radio that a bank had just been robbed and that 4 male perpetrators had

Deputy Smith was on patrol in his police car when he heard a report over the radio that a bank had just been robbed and that 4 male perpetrators had fled in a blue 1976 Ford pickup without a license plate. Several minutes later, Smith observed a vehicle matching the description given over the radio except that it had license plates. He followed the truck and after turning on his flashers, ordered the driver of the truck to pull over to the side of the road, which he did. Smith approached the truck and observe 3 men and 1 woman in side. Each was nervous and upset by the fact that they  had been stopped. After Smith ordered the occupants out of the car, he observed a bulge in the driver's pocket. He frisked the driver and found a weapon.

Was Deputy Smith justified in stopping the vehicle and frisking the driver?