An off-duty officer with the Chicago Police Department has died and a woman is in critical after a carbon monoxide leak earlier this week. 

According to ABC News, the officer—identified as 36-year-old Xu Meng—and a 29-year-old woman whose name has not been released were found unresponsive on Tuesday evening after fire fighters responded to reports of a carbon monoxide leak.

Both victims were transported to a nearby hospital where Meng was pronounced dead. The woman is presently listed in critical condition.

No further details about the incident have been released.