(CNN) -- Two adults were arrested Monday after a mob attack on a driver on the East Side of Detroit last week left the victim in a coma, authorities said.
The two arrests follow the weekend jailing of two teenagers, one of whom was charged Monday as an adult.
The names of the two adult men -- ages 24 and 30 -- were not released.
Detroit Police Sgt. Michael Woody said that on Wednesday a group of a dozen or so other people attacked Steven Utash, a 54-year-old grandfather, after a car accident.
Bruce Edward Wimbush, 17, was charged Monday with assault with intent to murder, Wayne County prosecutor Kym Worthy said in a news release.
A fourth suspect, a 16-year-old boy, was also arrested in connection with the attack, but prosecutors are still deciding if he will be charged as an adult.
"By no means are we through with this investigation," Woody said, hinting there might be more arrests soon.
Utash was driving through the east side of town in his truck when he inadvertently struck a young boy who had stepped into the road, Woody said.
The man immediately stopped his vehicle to help the boy when he was allegedly "severely beaten" with "fists and feet," the prosecutor's release said.
Utash remains hospitalized in a medically induced coma.
"It's hard to see him lying in the bed, not knowing who we are, where he is or what's going on," Felicia Utash, the victim's daughter, said about her father.
She, her brother and sister set up a GoFundMe page for their father, who they say doesn't have insurance. Donations have exceeded $115,000.
The prosecutor's office said the boy who was struck by Utash's truck was taken to a local hospital and treated for a leg injury. Woody said that he was unsure of the extent of the 10-year-old's injuries but that he is at home recovering from the accident.
Police have not revealed a motive for the attack on Utash but said the investigation is widening and they expect to make other arrests.
Detroit Mayor Mike Duggan and City Council President Brenda Jones issued a statement Friday in response to outrage over the incident, asking for calm and patience from all Detroiters.
"This senseless vigilante style attack is not the essence of who we are as Detroiters and will not be tolerated," the statement said.
CNN's Janet DiGiacomo contributed to this report.