SANFORD, Fla. — The Seminole County Sheriff’s Office is continuing to investigate a shooting at a Sanford bar and grill early Sunday that left 10 people injured, including Houston Texans wide receiver Tank Dell.

The shooting occurred at a private event held Saturday night at Cabana Live, dubbed the “Nobody Leaves Sober Pool Party,” Sheriff Dennis Lemma said during a news conference Monday afternoon.

A 16-year-old male is accused of firing a 9mm handgun after a physical altercation broke out during the event.

The teen faces four charges related to the shooting, including one count of attempted murder, according to Lemma.

During Monday’s news conference, Lemma released additional details about a second shooter from across the room, who he said may have returned fire in self-defense. Investigators are still working to identify that person and determine his or her involvement in the “shootout,” Lemma said. The sheriff noted that the second gunfire came from a 45-caliber handgun.

Lemma shared video of the shooting during the news conference and pointed out several muzzle flashes from both sides of the venue area where the shooting occurred, with deputies finding several shell casings from both guns on the floor of the venue.

Lemma praised the quick actions from a security guard who tackled the teen shooting suspect, saying he “acted heroically,” and that “he literally tackled the guy from behind.”

Lemma said 200 people attended the event, which cost $10, and promoters hired 10 armed security guards. Lemma also noted that the promoters did not get a proper permit for the even

Around midnight on Sunday, Lemma said a sergeant on routine patrol drove by the venue and saw a couple hundred vehicles in the location. Lemma said he initiated a patrol on behalf of the sheriff’s office and asked for an additional unit.

It was around 12:30 a.m., according to Lemma, that the sergeant and deputy heard shots fired from inside the establishment. They attempted to enter through the front door but were blocked by a large crowd of people rushing to exit the venue, according to Lemma.

The two law enforcement officers were able to enter through a backdoor, and at that time, a security guard brought them the teen suspect, already in handcuffs.

Detectives are still working to determine how the teen entered the private event with a gun, Lemma said, when security guards had turned multiple people away who were carrying weapons.

The teen shooting suspect from Volusia County does not have any prior arrests or criminal history.

Lemma said nine of the 10 people injured have already been released from the hospital, including Dell, who is from Daytona Beach. Lemma said Dell appeared to have been caught in the middle of the gunfire, as shown on the video footage.

The sheriff’s office is working to gather more witness evidence on what happened. Anyone with information is asked to call 1-800-423-TIPS (8477).