If someone crashes into your vehicle and that person is responsible for the crash they are then responsible for reporting their accident to their car insurance company.
You should also contact that persons insurance company as well so it's important you exchange insurance information with each other in an auto accident.
You need to know the persons insurance company and the persons name etc and then report the accident to their insurance company just in case they didn't report the accident.
Most drivers who're at fault in an accident are reluctant to report the accident to the insurance company so you should always report the accident yourself so be sure to get complete information from the driver who hit you.
If you have uninsured motorist coverage and the other person doesn't have insurance then you'll need to make a claim with your own insurance company to cover any damages or injuries and then you may have to take the person to court and sue them for any damages or injuries if they don't have any auto insurance.