The Los Angeles Chargers were without head coach Jim Harbaugh early on Sunday afternoon against the Denver Broncos.

Harbaugh, minutes before their game started at Empower Field at Mile High in Colorado, was seen entering the team’s blue medical tent on the sidelines to get checked out. It was unclear what the issue was at the time, and Harbaugh walked back to the locker room minutes later. He missed the start of the game as a result.

A few minutes into the game, the Chargers then confirmed that Harbaugh was dealing with an illness and was questionable to return. Defensive coordinator Jesse Minter stepped in to serve as the team’s interim head coach in the meantime.

Harbaugh’s brother, Baltimore Ravens head coach John Harbaugh, ended his news conference abruptly after learning of the situation in Denver, too. John was speaking after the Ravens’ 30-23 win over the Washington Commanders, and he left to call his brother and check in, according to The Athletic’s Jeff Zrebiec. It’s unclear if he got through or was able to speak to Jim.

Just past the midway point of the first quarter, Harbaugh returned to the sidelines and took back over. Further specifics about his illness aren’t known. He came back out just in time to watch quarterback Justin Herbert throw a 38-yard touchdown pass to Kimani Vidal, too, which put the Chargers up 10-0.

Harbaugh is in his first season with the Chargers this fall after a nine-year run at Michigan, which he capped with a national championship last year. It marks his first job back in the league after he spent four seasons leading the San Francisco 49ers from 2011-2014. The Chargers entered Sunday’s game with a 2-2 record.