11 men have been assaulted in downtown Wilmington, North Carolina since January 2018, police say

Police in Wilmington, North Carolina are investigating assaults against 11 men, including members of the military, near downtown bars, since January 2018, authorities said.

The victims were assaulted around the time the bars closed, Wilmington police said. Some victims were robbed. Police have identified four victims who may have been sexually assaulted. Seven victims were military personnel, police said.

In two Facebook posts this week about the alleged assaults, Wilmington police didn’t say if investigators believe the crimes are connected. Police declined to provide additional information on Wednesday, including details on the victims and locations of the crimes.

Authorities declined to make copies of police reports available at this time “to protect the integrity of this investigation and the safety of the victims,” the Facebook post said.

Investigators believe the assaults could have started as far back as January 2018. There was a four-month lag in time between some assaults, and the locations of the crimes and other details are limited because of the victims’ conditions then, police said.

Some of the initial reports came in as misdemeanor crimes, such as breaking and entering, with limited details, which made the investigation challenging, authorities said.

Mark Mueller, the co-owner of Waterline Brewing Co. in downtown, told CNN affiliate WWAY the brewery usually takes steps to keep its employees and patrons safe.

“You never want to have one person closing. You never want to have someone walk to their car by themselves. You never want to have someone walking home alone,” Mueller said.

Wilmington police say they have increased patrols in the downtown area. Authorities also encourage customers not to leave their drinks unattended and to travel in groups.

Authorities are working with state and federal agencies in the investigation.