First reports are positive however with Fox Cricket's Neroli Meadows reporting "he never lost consciousness" after being struck in the neck.
"He has been taken to hospital," she said. "It was quite distressing at the time. His dad came around and was visibly upset, his sister came as well. They've gone to hospital in a separate car to support Karunaratne. The manager from Sri Lanka was also with him."
The concern was immediate with training staff and medical personnel surrounding the star batsmen as Australia grouped together nearby.
After roughly 10 minutes of laying on the pitch Karunaratne was lifted onto the stretcher with a neck brace on. As he was loaded onto the stretcher Cummins was quick to check in on his opponent.
He was driven straight from the field and loaded into an awaiting ambulance where he'll go have further medical attention.
Sri Lanka coach Chandika Hathurusingha provided an update on the opener following the end of play on day two.
"At the moment he's being assessed in the hospital, but before he is leaving I spoke to him and he's ok," he said to Meadows.
"He's never been unconcious but he's in pain. It was a bit scary at the start because of the way he fell backwards and threw the bat away and then he was not moving, but the umpires and officials said he was conscious all the time so that was good news.
"I think everyone in our team is upset with what happened but that's where the game goes. We lost a little focus after that and unfortunately lost three wickets but they're ok now."
The Sri Lankan opener was closing in on a 50 as Sri Lanka started well at Manuka Oval.
Cummins was coming around the wicket to the left-handed Karunaratne and was fell straight to the ground.
The 30-year-old laid on the ground for 10 minutes as medical staff brought on a stretcher, getting Karunaratne into an ambulance immediately after leaving the field.
Channel Seven commentator James Brayshaw said it was "raw" for the cricket community after a bouncer led to Phil Hughes death on the field in a Sheffield Shield match in November 2014.
"It is all a bit flattening, isn't it?" he said. "No-one likes to see, in any sport, anyone injured. It is all pretty raw for us in the cricket family, isn't it?"
Former Australian star Mike Hussey echoed the words of Brayshaw at the end of the day's play.
"Good news he never lost consciousness for one, good news he's doing ok in the hospital, in a bit of pain obviously but lets hope he can come back and play a bit of a part in the rest of the Test match."
