The Hunt County Sheriff's Office is working a scene of a standoff at a residence in the Rolling Hills area near Lone Oak.
An ambulance has also been called to the scene as of 1:45 p.m.
"We've got a mental patient that has barricaded himself in the home," said Sheriff Randy Meeks. "He does have a weapon and it appears he assaulted his brother."
Meeks said officers have created a perimeter around the residence.
"Right now we have called out SWAT," Meeks said, adding the officers are awaiting the arrival of the tactical officers before making a decision as to how to proceed.