New York (CNN) -- New York authorities are searching for a gunman wanted in the killings of four people shot to death inside a Long Island pharmacy, police said.
Police described the suspect, who was also caught on surveillance video, as a thin man about 5 feet 8 inches tall. He was unshaven or had a dark beard and mustache along with short, dark hair.
He was wearing a white baseball hat, sunglasses, a dark-colored hooded sweatshirt, blue jeans and dark shoes, authorities said. He was wearing a black backpack.
The shootings, which took place Sunday morning at Haven Drugs in Medford, occurred during a robbery of the pharmacy, Suffolk County police said. The suspect stole prescription drugs after the shootings and fled on foot, authorities said.
Police identified the dead as Raymond Ferguson, 45, and Jennifer Mejia, 17, both pharmacy employees, as well as customers Bryon Sheffield, 71, and Jamie Taccetta, 33.
Mejia's death comes just before her prom -- scheduled for Wednesday night -- and her graduation from Bellport High School on Thursday, said school secretary Maryann Malcolm.
Police said the suspect should be considered "armed and extremely dangerous."
Calls to Haven Drugs were not immediately returned Monday.
Police are offering a reward of up to $5,000 for information that may lead to an arrest of the suspect.
CNN's Jason Kessler, Max Markham, Jordana Ossad and Rachel Garrett contributed to this report.