Police heard gunshots behind the apartment complex just before 6 p.m. Thursday. (CBC)

Police continue to guard the Halifax hospital where Jimmy Melvin Jr. is recovering from a bullet wound.

Melvin, 26, was rushed to the QEII Health Sciences Centre in serious condition Thursday night after he was shot in the abdomen.

Halifax Regional Police said the shooting is a result of a dispute in the drug trade.

Const. Jeff Carr, spokesman for the police service, said officers were posted at the hospital to ensure the safety of patients.

Since Jimmy Melvin Jr. was released from prison three weeks ago, his father and an associate have also been targeted in shootings. (CBC)

"It is because of who the victim is in relation to this matter, and obviously there is a potential there for further incidents," he said Thursday night.

Police had Melvin under surveillance and were close enough to hear gunshots coming from behind a large apartment complex in Armdale just before 6 p.m.

Moments later, someone called 911 to report that a man inside was suffering from a gunshot wound.

Police later took four people into custody. No one has been charged.

"We have put unprecedented resources behind this," said Carr, adding that police can't prevent every incident.

Melvin was released from jail three weeks ago after witnesses in a home invasion case recanted their stories and the charges against him were dropped.

Within days, his father, Jimmy Melvin Sr., a convicted drug trafficker, was shot at outside a pizza shop in Spryfield. He was injured as he dodged gunfire.

The next day an associate of Melvin Jr.'s was shot and wounded outside the IWK Health Centre in Halifax.