It appears obvious from the footage Groenewegen forces his Dutch compatriot into the barrier.
Reports indicate Jakobsen is now in a serious but stable condition.
His team have now (8am AEST) confirmed this report.
"Fabio Jakobsen’s situation is serious but at the moment he is stable," the Deceuninck–Quick-Step statement reads.
"Diagnostic test didn’t reveal brain or spinal injury, but because of the gravity of his multiple injuries he is still kept in a comatose condition and has to remain closely monitored in the following days at the Wojewódzki Szpital in Katowice.
Earlier this morning (AEST) the race doctor gave a report on Jakobsen's fight for life.
"We did everything that could be done," she said as reported by Polish news site naszosie.pl. "The working conditions were very hard, it is a very serious craniocerebral trauma, a broken palate, so it was difficult to intubate, but the laryngeal tubes and oxygen were connected all the time.
"We maintained the level of saturation and life activities. The heart was working well, it was maintaining the right pressure.
"This cyclist is very seriously injured and is life threatening. The palate and the upper respiratory tract were crushed, but he managed to intubate, he went to the hospital, but lost a lot of blood. He is alive after all, he is with us and let's hope we win."
Marc Sarreau (Gropuama FDJ) also came down heavily in the crash and is OK but will not start Stage 2.
Jakobsen was later awarded the sprint victory with Sarreau second.
The UCI has referred Groenewegen to its disclipinary commission over the incident.
“The Union Cycliste Internationale (UCI) strongly condemns the dangerous behaviour of rider Dylan Groenewegen (Jumbo-Visma), who sent Fabio Jakobsen (Deceuninck–Quick-Step) into the barriers a few metres from the finish, causing a collective crash at the end of the first stage of the Tour of Poland,” the governing body's statement read.
“The UCI, which considers the behavior unacceptable, immediately referred the matter to the Disciplinary Commission to request the imposition of sanctions commensurate with the seriousness of the facts.”
Jumbo-Visma released this statement via Twitter:
Deceuninck–Quick-Step are concentrating on Jakobsen's condition.
Many current and former riders also condemned the sprint course.
SBS Cycling commentator and analyst Dave McKenzie had this to say.