Philip Nelson, Minnesota quarterback last season, has been arrested for assaulting a former Minnesota State University, Mankato (MSU) linebacker, who is reportedly "fighting for his life."

According to the Minneapolis Star Tribune, Nelson, who was transferring from Minnesota to Rutgers, and another person sucker punched Isaac Kolstad, a USM linebacker. After the initial contact, Nelson and the unknown other person kicked Kolstad in the head when he fell.

"He [Kolstad] was knocked out on his feet," Stephanie Stassen, a 25-year-old graduate student who said she witnessed the attack, told the Star Tribune. "He fell straight back and smoked his head on the pavement.

"He didn't try to brace himself or catch himself."

She said "the noise of him hitting his head was so loud" and that the assault seemed to come "just out of nowhere."

The Blue Earth District Court charged Nelson, 20, with first-degree and third-degree assault early Monday morning following his arrest. He was kept in jail until his hearing later in the day.

Isaac's father, Blaine, posted an update on his 24-year-old son's status Sunday night on the website CaringBridge.org.

"Isaac suffered a severe head injury early this morning. He is currently in Critical condition and fighting for his life," he wrote. "He is young and strong, but the battle he has in front of him is enormous. We do not yet know the full extent of his injuries. He is very sick. Please pray for Isaac and all of those involved."

Both Nelson and Kolstad are Mankato, Minn. natives. Nelson previously played for the Minnesota Gophers before transferring to Rutgers earlier this year. Kolstad graduated from MSU in Dec. and was working as a sales representative for an insurance company, NJ.com reported.

There is no word yet on what sparked Nelson's assault of Kolstad, but Rutgers' athletic department is waiting for more information before making a formal statement.

"We are in the process of gathering information on the situation and reserve comment until the legal process is complete," spokesman Jason Baum said in a statement on Sunday.