Three teenagers and an adult were shot Wednesday night in the parking lot of a strip mall in Temple Hills, Maryland, according to police, who are working to determine a suspect.The shooting happened around 6:25 p.m. when a suspect or suspects shot at a group, police said.The victims suffered what appeared to be non-life threatening injuries, the Prince George’s County Police Department tweeted.The mass shooting, which occurred only a few miles from the Maryland-Virginia state border, came as police in neighboring Virginia are investigating a shooting that left six Walmart employees dead after a manager opened fire in a break room before dying by suicide.Both the non-profit and CNN define mass shootings as those in which four or more people are shot, not including the assailant."