Five Chinese nationals and two Vietnamese border guards were killed Friday in a shooting incident at the border of Vietnam's northern province of Quang Ninh, according to local media reports.

The Chinese victims were among a group of illegal immigrants trying to enter Vietnam, according to the reports.

They were detained by Vietnamese officials and during the procedure of repatriation, some of them allegedly snatched a guard's gun and opened fire, killing a Vietnamese border guard instantly.

The guards then took "legitimate self-defence measures" and tried to approach and arrest the group, who had by then holed up and tried to destroy the office, according to the reports.

The situation was brought under control at 3:15 p.m. local time, costing the lives of seven people.

China's Foreign Ministry said on its official Sina microblog Friday night that it was aware of the reports and taking steps to verify them.