(CNN) When a military charter passenger plane skidded off a runway in Florida and landed in the water Friday, the Jacksonville Fire and Rescue units were ready to help.

After all, they had trained for a similar incident that same day with the marine units, the agency tweeted.

The aircraft -- carrying 136 passengers and seven crew members -- slid into St. Johns River while trying to land, authorities said. It was returning from the Guantanamo Bay military station in Cuba.

"Ironically," the fire and rescue department tweeted, "our Special Operations team trained for an incident like this today with the marine units."

Ironically, our Special Operations team trained for an incident like this today with the marine units. — MyJFRD (@JFRDJAX) May 4, 2019

Twenty-one people were transported to nearby hospitals in good condition, Jacksonville Fire Rescue Public Information Officer Tom Francis said. They included three children, among them a 3-month-old, Capt. Mike Connor told CNN affiliate WJXT . The baby was kept at a hospital overnight for observation and was released Saturday.

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