CHICAGO (CBS) — Three people with ties to Hawthorne Race Course were in custody Thursday morning, after a man was stabbed to death at the racetrack Wednesday night.

Officials said, around 6 p.m. Wednesday, two workers were fighting in the back stretch of Hawthorne, where stable hands have living quarters. A Hawthorne spokesman said the two don’t work directly for Hawthorne, but were hired by horse trainers and were stationed with them at the track in west suburban Stickney.

Stickney police said, by the time officers arrived, one man had been stabbed to death near the stables. A man and a woman immediately were taken into custody.

“Interviews were conducted at the racetrack. Two people of interest were brought to our station, interviewed, and they are still being held,” Stickney Police Chief John Sladetz said.

Another man was tracked to a location near Midway International Airport around 4 a.m. Thursday, and police brought him in for questioning.

The chief said the motive for the stabbing has not yet been determined.

“We don’t know if it was a dispute, if it was a robbery. We don’t know,” he said.

The racetrack said the ongoing death investigation would not halt afternoon races at Hawthorne.

“People pull together. I mean, are the upset? Of course. Are they concerned? Of course. But what you do is you pull together, and everybody looks out for one another. And that’s how we treat it not only with our employees here at Hawthorne, but that’s how many people living on the back stretch treat it as well,” Hawthorne spokesman Jim Miller said.

The three people in custody were not being called suspects Thursday morning, only persons of interest.

No charges had been filed as of late Thursday morning.

The victim’s name has not been released. Sladetz said the man was in his 30s.