FORT HOOD (November 17, 2009)—An emergency code sent by accident Tuesday evening led to a brief lockdown at Carl R. Darnall Army Medical Center on Fort Hood, where nerves are still frayed 12 days after the shooting rampage at the post’s Soldier Readiness Center that left 13 dead and 29 injured.

The code, received at 5:13 p.m. Tuesday, indicated that an armed intruder might be in the hospital and staff members immediately called 911, the post said.

Fort Hood Emergency Services responded within four minutes and determined it was a false alarm, the post said.

The code was canceled at 5:40 p.m., the post said.

“When codes are called, patient care continues while security measures are assessed and, if needed, put into place,” Fort Hood said.

“The immediate and efficient response of Fort Hood security and hospital personnel reinforces that on-post security measures are working as they should,” the post said.