NFL referee Larry Smith left the field on the back of a cart on Sunday after appearing to suffer a serious leg injury in the first half of the Texans-Jaguars game.

Smith was the main referee for the NFL London game at Wembley Stadium but his afternoon finished early when he collapsed to the turf in agony during the first quarter.

Video of the scary incident showed Smith, who is a longtime Big Ten official and finally got the call to the NFL last season, appear to slip on the wet turf, causing a non-contact injury to his leg.

After falling to the ground hard, he tries to get back to his feet but immediately feels excruciating pain and falls back to the turf, where he is surrounded by players. 

With the game stopped, he is then tended to by medics, with one of his fellow officials even taking a knee alongside him while he received treatment.

Eventually, Smith was loaded onto the back of a medical cart and driven off the field, where he took off his cap and raised it to the fans as they applauded.

Alongside his role in the NFL, Smith serves as the principal of a middle school in Kansas.  

The game itself continued with six officials rather than seven, and Shawn Hochuli took up the majority of Smith's duties, according to multiple reports.

In the second half, the Texans took a 10-point lead over the Jaguars, with Jaylin Noel hauling in a touchdown catch from CJ Stroud.

For the Jags, meanwhile, it was running back Bhayshul Tuten enjoying a positive day, scoring two touchdowns for his team.