SAN FRANCISCO (KRON) – The San Francisco Police Department is investigating an early morning shooting in the city’s Potrero Hill neighborhood.

Around 4:07 a.m. officers responded to the area of 16th and Utah streets after reports of shots fired and found an armed security guard.

“Witnesses reported that the security guard, an adult male, was patrolling the area when he was confronted by an unknown adult male subject,” an SFPD press release states. “Witnesses said the subject charged at the security guard with a knife. It was at that moment that the security guard shot the subject with his firearm. Medics were summoned but, despite life-saving efforts, the subject was pronounced deceased at the scene. The security guard remained on scene and is cooperating with investigators.”

No arrests were made, the SFPD stated, though it is “an open and active investigation,” according to the news release.

Anyone with information regarding this investigation is asked to call the SFPD tip line at 1-415-575-4444 or text a tip to TIP411 and begin the text message with SFPD. Anonymous tips are accepted.