An employee of the NFL, whose headquarters are in the New York City building targeted in a deadly shooting Monday, was “seriously injured” in the attack, league commissioner Roger Goodell said in a staff memo.

“As has been widely reported, a gunman committed an unspeakable act of violence in our building at 345 Park Avenue. One of our employees was seriously injured in this attack,” Goodell wrote in the memo, per ESPN. “He is currently in the hospital and in stable condition. NFL staff are at the hospital and we are supporting his family.”

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Goodell did not identify the NFL employee who was injured. The NFL believes that “all of our employees are otherwise safe and accounted for, and the building has nearly been cleared,” the commissioner wrote in the memo, sent early Tuesday morning.

According to the AP, authorities identified the attacker as Shane Tamura, 27, of Las Vegas, had a “documented mental health history,” according to Police Commissioner Jessica Tisch. His motive remained unknown.

Four people, including an off-duty New York City police officer, were killed in the incident and another person was critically wounded in the Midtown Manhattan shooting, authorities said. According to surveillance video, the shooter exited a BMW parked outside the building just before 6:30 p.m. Monday carrying an M4 rifle, per the AP. The attacked then entered the building’s lobby and shot and killed the NYPD officer, who was working a corporate security detail at the location, and then shot a woman who tried to take cover as he sprayed the lobby with gunfire, the Associated Press reported.

Other businesses with offices located in the building included private equity firm Blackstone, KPMG and real estate management and development firm Rudin Management.

Goodell, in the memo, said the NFL is “deeply grateful to the law enforcement officers who responded to this threat quickly and decisively and to Officer Islam, who gave his life to protect others.” He also wrote that there will be “an increased security presence at 345 Park Avenue in the days and weeks to come.”

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