PETERSBURG, VA. >> A 20-year-old Virginia man walked into a plasma donation center during a Fourth of July community cookout, asked to use the restroom, then began randomly stabbing people with a long knife as customers and staff members ran for cover, authorities said Friday.

Jairique Shannon had donated plasma at Octapharma Plasma in Petersburg at least once before and authorities do not know why he attacked people at the center on Thursday, said Commonwealth’s Attorney Cheryl Wilson. Three people were hurt and remained hospitalized Friday.

“There’s no information that he had any grudge against anyone, and at this point we don’t have a motive,” Wilson said.

A recording released by broadcastify.com captures the chaos after the attack began.

“The suspect possibly has a machete. Units use caution,” the dispatcher can be heard saying on the recording. A first responder can be heard saying that one of the victims lost a finger.

Police said the attack took place as patrons were inside donating blood. Wilson said the center was also hosting a “customer appreciation cookout” outside to thank residents for donating plasma.

The business sits in a commercial district near a bank and restaurants on the south side of the city about 25 miles (40 kilometers) south of Richmond.

Irene Banks told WWBT-TV that police praised her daughter, a manager there, as a “hero” for stopping the attacker before officers arrested him.

“She took the man down, they said, my daughter did,” Banks told the television station.

Wilson said that when police arrived, Shannon was outside waiting for them.

“They did not have any issues with arrest; he was compliant at that point,” Wilson said.

Shannon has been charged with three counts of malicious wounding and is being held at the Riverside Regional Jail. He is scheduled to be arraigned Monday in Petersburg General District Court.

A spokesman for a Petersburg hospital that received three patients after the attack said Friday morning that one male in critical condition had been transferred elsewhere. A female was in fair condition and another female was in good condition, Southside Regional Medical Center spokesman Brandon Seier said.

Petersburg Police said in a tweet that at least one victim’s injuries were considered life-threatening.

Octapharma Plasma, based in Charlotte, North Carolina, issued a statement Friday saying the company is “heartbroken.”

“Our sole focus remains on supporting those involved and impacted in Thursday’s event,” the statement said. “We are working with authorities at this time to provide any help and information necessary.”

Octapharma’s website says it employs more than 3,000 U.S. workers and operates more than 80 plasma donation centers in 26 states.

Shannon was also charged with animal cruelty after police executed a search warrant at his Petersburg home, Wilson said. Jail records show that the charge involved the torture or mutilation of a dog or cat causing death.