A gunman opened fire inside a crowded Oklahoma City restaurant during dinnertime Thursday evening, wounding three people before he was shot dead by two men in the parking lot, police said Friday.

The shooting victims in the restaurant included two young girls, whose identities were not made public, and a 39-year-old woman, Natalie Giles, Oklahoma City police said. A fourth person suffered a broken arm when he fell running away from the gunfire, police said.

All of the victims were in good condition as of Friday morning, according to authorities.

The incident unfolded around 6:30 p.m. CT at Louie's Grill and Bar, a pub along Lake Hefner, when police said Alexander Tilghman, 28, of Oklahoma City stood in the doorway and started shooting, seemingly at random.

After firing several times from the pub's entrance, police said, Tilghman was fatally shot outside by two bystanders: Juan Carlos Nazario and Bryan Whittle, who had grabbed handguns from their vehicles, Oklahoma City Police Capt. Bo Mathews said on Friday.

"They stopped an incident that was very, very bad," Mathews said. "We had no idea what he was going to do after he left Louie's restaurant."

The two citizens did not know each other and arrived at the scene separately, Mathews said.

Gerald Konkler of the Oklahoma Council on Law Enforcement Education and Training confirmed to NBC News that Nazario has an armed security guard license. Konkler said Tilghman also had such a licence, and his record showed no disciplinary action.

"I was just there enjoying the lake scenery and heard shots," Nazario, 35, told NBC News. "At that point I zoned out and had to take action. Just glad no innocent bystanders' lives were taken, and unfortunately a life was lost, but he had a choice to drop the weapon and chose otherwise."

Whittle, 39, told USA Today that he "just did what needed to be done to stop the threat. Nothing special."

"A lot of people would have done the same given the situation," Whittle said. (Police initially misspelled Whittle's name as Wittle.)

Oklahoma requires a license for handguns to be carried, either openly or concealed. Two weeks ago, the state's Republican governor, Mary Fallin, vetoed a bill that would allow adults to carry guns without a permit or training.

“I am thankful that under the concealed-carry and open-carry laws that I have signed as governor, two armed citizens had the ability to protect and save the lives of our fellow Oklahomans," Fallin said in a statement on Friday. "This is not the time to debate the NRA’s efforts to repeal Oklahoma’s regulations assuring safety and training for those who carry guns. This is a time to offer up prayers to the victims of this tragedy.”

May 25, 2018 / 9:19 am: Official news release regarding last night's shooting at Lake Hefner. Press conference will be carried live on our Facebook page at 11:30 this morning. pic.twitter.com/i06ytafSlz — Oklahoma City Police (@OKCPD) May 25, 2018

Mathews, of the Oklahoma City police, said he did not expect Nazario or Whittle to be charged for the fatal shooting.

Officials don't know the gunman's motive, but said they had no reason to suspect terrorism.

Tilghman had not been on local authorities' radar for over a decade. Mathews said the last contact police had with him was in 2003, when he was arrested as a 13-year-old juvenile for assault and battery. No additional details were provided about that arrest.

A YouTube account that apparently belonged to him painted a picture of a disturbed, paranoid individual.

In a video last month posted to the account, Tilghman, using the username Yahweh Rules2, insisted that he was under "hardcore demonic attack" and gave out his phone number, pleading for "real people" to contact him.

"My life is in danger and stuff so I hope to hear from you guys, some real people, soon," he said, looking straight at the camera while sitting on a couch.

The final video on the account was posted three weeks ago and shows a squirrel that Tilghman said was "a demon following me everywhere."

Witnesses to the restaurant shooting said Tilghman was wearing protective earmuffs and shooting glasses — the kind typically worn to a shooting range, according to Mathews.

"So it looked like he had made his mind up that he was going to discharge his firearm when he got there," Mathews said.

Police did not provide much detail about those injured by Tilghman. Dennis Will, the father of victim Natalie Giles and the grandfather of another victim, told NBC affiliate KFOR in Oklahoma that Giles was there for a birthday celebration for her daughter.

“It was beyond shock,” he said by phone from his home state, Tennessee. “I was supposed to go, but wasn’t able to make it.”

Police described the scene in the restaurant as chaotic as diners ran for their lives. More than 100 witnesses inside the restaurant were interviewed as part of the investigation.

Hal Smith Restaurants, which owns Louie's Grill and Bar, said the restaurant was closed on Friday.

"We are extremely thankful the situation didn’t escalate further, and that injuries were not more widespread," the Norman, Oklahoma-based restaurant group said in a statement, adding, "Our hearts are with the wounded during this incident."

CORRECTION (May 25, 6:41 p.m. ET): A previous version of this article misstated the name of the restaurant. It is Louie's Grill and Bar, not Louie's on the Lake.