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

Harbaugh was seen minutes before their game started at Empower Field at Mile High in Colorado, walking from the sideline into the team’s blue medical tent to get checked out. It was unclear at the time what was happening and Harbaugh walked back to the locker room minutes later. As a result, he missed the start of the match.

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, serving as the team’s interim head coach in the meantime.

Harbaugh’s brother, Baltimore Ravens head coach John Harbaugh, abruptly ended his press conference after also being informed of the situation in Denver. John spoke after the Ravens’ 30-23 win over the Washington Commanders, leaving to call his brother and check in, according to Jeff Zrebiec of The Athletic. It is unclear whether he got through or was able to talk to Jim.

Just past the midpoint of the first quarter, Harbaugh returned to the sideline and took over again. Further details about his illness are not known. He returned just in time to see quarterback Justin Herbert also throw a 38-yard touchdown pass to Kimani Vidal, putting the Chargers up 10–0.

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