Sounders defender Chad Marshall leaves practice in ambulance

Seattle Sounders defender Chad Marshall left training early and was rushed to hospital via ambulance after injuring his head or neck, reports The Seattle Times' Matt Pentz.

Marshall was in the middle of a practice drill at the Starfire Sports complex when he fell and hit his head on the ground. When he did not get back up, team doctors and medical staff quickly attended to him, supporting his head and neck until the ambulance came.

Marshall was then taken onto the ambulance with a stretcher. He wore a brace on his neck as his teammates looked on.

"We really don't know, so there's nothing I can really say," Sounders head coach Sigi Schmid said after the incident. "Obviously he fell, hit his head and we're taking all of the precautions. But at this stage, we don't know. We'll know more later."

"You're always going to err on the side of being conservative in a situation like this, any time it's a head or a neck," Schmid added. "That's what we've done and we'll see. I'm not a doctor so I can't make those analysis. Otherwise, I'd have a medical degree and be making more money than I'm making now."

Marshall, 31, has suffered a number of concussions during his 11-year career in Major League Soccer. He picked up a concussion in 2007 during his time with the Columbus Crew and could only play 12 matches that season.

Marshall was 2014's MLS defender of the year, the third time he won the accolade.

In the moments after, some of his friends and teammates tweeted to wish him well: