A motorcycle crash shut down an off-ramp on Route 57 westbound, as well as part of Mill Street on Saturday evening.
Agwam police told CBS 3 that the crash, which happened around 6 p.m., involved just the motorcycle.
The rider suffered serious injuries, and he was taken to Baystate Medical Center where he is listed in critical condition.
Initial reports said alcohol and speed appeared to be factors in the crash.
The department's accident reconstruction team is working with the reconstruction team from the Massachusetts State Police on the investigation.
There is no timetable on when roads will reopen.
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