Saw three bright lights traveling from west to east at low altitude. Had a fourth light blinking. Was on a trajectory be teen Funkstown and Meritus hospital. Was very low and lights seemed to be about 100 feet apart. I pulled over and got out of car. There was no sound and I could not see any shape. I sighted it again from eastern Blvd in the area of the YMCA about ten minutes later heading northwest. My girlfriend saw it in the vicinity of Hagerstown airport at about 1840 hours and lost sight. No more than 100 feet altitude.