Andretti Autosport driver Justin Wilson is in a critical condition after suffering severe head injuries following an accident at Pocono Raceway, according to an official medical update issued on Sunday evening.

Wilson was struck in the head by debris from the car of Sage Karam which had spun into the wall near the end of Sunday's ABC Supply 500, the penultimate round of the 2015 Verizon IndyCar Series.

It appeared that part of the nosecone from Karam's car was sheared off and thrown into the air by a violent contact with the wall in turn 1 on lap 179 of the 200-lap race.

Wilson rounded the corner and had no warning of the incident before he was caught up in the debris field. The nosecone made a direct impact with the cockpit area of Wilson's car.

Medical teams were immediately on the scene to extricate Wilson from the car. He was stretchered to a waiting ambulance and driven to the in-field medical centre, where he was taken direct to the medical helicopter and airlifted to Lehigh Valley Health Network Cedarcrest Hospital in Allentown, Pa.

A press release from the IndyCar Series said that the 37-year-old is currently in a coma and in critical condition while undergoing further evaluation. Additional updates regarding Wilson's condition will be released when available.

Wilson's wife Julia and brother Stefan - himself a former Indy Lights competitor - are reported to be en route to the hospital to be with him, with former IndyCar champion Tony Stewart reportedly loaning his private plane to the family to get them to Pennsylvania as quickly as possible.

The IndyCar Series added that it sent its thoughts and prayers to Justin, his family and to Andretti Autosport during this difficult time, sentiments very much shared by everyone at

Wilson has competed in US open wheel racing since 2004, after a season in Formula One racing for Minardi and Jaguar. Wilson took four wins in 54 starts in the Champ Car World Series, and to date has three wins in 104 starts in the IndyCar series.

Karam was also taken to hospital after the accident, although in his case it was via ground transport. The 19-year-old was able to climb out of his car but appeared shaken and bruised, sitting on the side of his car while waiting for the ambulance to arrive.

The race eventually finished under yellow, with Wilson's team mate Ryan Hunter-Reay picking up his second win of the season. However, Hunter-Reay's first thoughts when he arrived in victory circle were to ask about the condition of his team mate, and celebrations were muted as the paddock awaited word of Wilson's status.

"It's a tough one right now. Our thoughts and prayers are with Justin right now," team owner Michael Andretti commented.

"Obviously, first and foremost, we're thinking about Justin," said Hunter-Reay. "I thought Justin was okay the whole time. I thought he was in an ambulance and was going to get a check.

"All I know is that he was unconscious, he was not responding and he was airlifted.

"That's all very bad. I'm very worried right now," he admitted. "With heads exposed and when you get flying debris, it's a bad luck deal. Our thoughts are with him. I know him and his family well, they're great friends of ours. Really, really just thinking about Justin right now."

"Right now my thoughts are with Justin Wilson," echoed Ryan Briscoe, who is himself currently subbing for James Hinchcliffe at Schmidt Peterson Motorsport after the popular Canadian was seriously injured in a practice accident at Indianapolis in May. "We're wishing him the best."

"I heard Justin had a big accident and I hope he is okay," said a concerned Takuma Sato, who like Wilson is another graduate from the F1 paddock. "I don't know the status right now but I wish him a super speedy recovery."

The crash was one of a number of incidents in Sunday's race. Another of Wilson's team mates, Marco Andretti, spun out on lap 138 with apparent suspension failure and was seen limping to the ambulance with assistance from marshalls, but he was later checked and cleared from the medical centre with simple bruising to his right knee.

Ganassi's Charlie Kimball had a serious accident in practice on Saturday when his car spun into the wall and then rode up into the catchfence, but Kimball was unhurt save for a cut to the chin requiring stitches, and he was able to participate in Sunday's race as normal.