CHICAGO — The nation’s air travel system slowly began to recover Saturday after an alleged act of employee sabotage at a large regional air traffic control center brought Chicago’s two international airports to a halt.

At the height of the travel misery Friday, more than 2,000 flights in and out of O’Hare and Midway airports had been canceled, sending waves of travel disruption rippling across the country.

Authorities say a contract employee started a fire Friday morning in the basement telecommunications room of a control center in the Chicago suburb of Aurora and then attempted to commit suicide by slashing his throat. Brian Howard, 36, of Naperville was charged with destruction of aircraft or aircraft facilities, a felony. The FBI said Howard remains hospitalized and no court date has been set.

As of Saturday afternoon, total Chicago flight cancellations for the day stood at more than 700.

Howard entered the building around 5 a.m. Friday, and about 30 minutes later posted a suicide note on Facebook in which he apologized to loved ones for leaving “a big mess,” according to a federal criminal complaint.