A Jeep Grand Cherokee was involved in a two-vehicle crash near Ayer and Sumner streets in Harvard Wednesday | Photo: Alex Vucha.

A 72-year-old man is in critical condition after he possibly suffered a medical emergency which caused him to crash into another car in downtown Harvard Wednesday morning, police said.

The Harvard Fire Protection District and Harvard Police Department responded around 10:52 a.m. Wednesday to North Ayer Street and Sumner Street for a report of a two-vehicle crash.

Police officers found one of the drivers, a 72-year-old Harvard man, unconscious and not breathing on the sidewalk near the scene, according to Harvard Deputy Police Chief Tyson Bauman.

Officers applied an AED and administered CPR until paramedics arrived.

Paramedics took over treatment and transported the man by ambulance to Mercy Harvard Hospital. He was later transferred to Mercyhealth Hospital and Trauma Center in Janesville for additional treatment, Bauman said.

The 72-year-old man was driving his vehicle eastbound when he possibly experienced a medical emergency, police said. He remains in the hospital in critical condition.

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The accident remains under investigation by the Harvard Police Department and the McHenry County Regional Major Crash Assistance Team (MCAT).