A 3-year-old boy accidentally shot his 2-year-old sister after a man allegedly brought a gun to a Florida gathering, authorities said Saturday.

The girl underwent surgery and was in “exceptionally critical condition,” said Polk County Sheriff Grady Judd at news conference.

The shooting occurred just before midnight Friday as three men were watching a basketball game in Lakeland, he said. One of them, later identified as Kevonte’ Wilson, 23, allegedly brought a loaded .380 handgun and hid it between couch cushions where the children were playing, the sheriff said.

The three grabbed the girl and rushed her to a hospital in a vehicle but were “t-boned” by a motorist who turned in front of them en route, injuring all the occupants, Judd said.

“At that time a good Samaritan had stopped,” he said. “And the good Samaritan took the baby and a male to the hospital.”

The adults in the vehicle have since been treated and released, Judd said.

He said he was not able to identify the children’s parents under Florida law. The mother was away visiting her sister at the time, he said.

The host, Chad Berrien, 24, was charged with possession of marijuana and maintaining a house for drug use after a search warrant allegedly turned up cannabis and paraphernalia, Judd said.

Barrien is not culpable in the shooting, he said.

“It just appears to be a horrible, tragic accident that should have never have occurred,” Judd said.

Wilson was charged with failing to safely store a firearm, carrying a concealed firearm and possession of marijuana, he said. He could face more allegations as the investigation continued, Judd said.

The third man watching basketball was not arrested.

The boy was placed with his grandmother. “The 3-year-old is not going to be charged,” Judd said.