Very sad situation. Here are some more details from WFAA:

A Central Texas police chief working an off-duty security job at a bar in Temple has been shot and critically wounded during a struggle with a customer.

Temple police say Darrell Allen, the chief in Marlin, has been undergoing surgery at Baylor Scott and White Hospital after the shooting early Sunday. He was reported to be in critical condition.

We will monitor this story and update with any additional information.