CONCORD (CBS) – Two teenagers have been accused of planting homemade bombs on the MBTA commuter rail tracks in Concord Tuesday afternoon.

Firefighters were responding to a brush fire just before 5 p.m. near the Sudbury Street crossing on the Fitchburg commuter line when they found two bottles.

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Sources told WBZ-TV both contained liquid chemicals that had the potential to explode. Transit police described the devices as “incendiary.”

“They were made up of a plastic bottle that contained 2 liquid chemicals that can be purchased over the counter,” the agency said in a statement Wednesday.  “When the chemicals interact with one another, over a period of time, they heat up and cause a flash fire.”

Officers shut down the tracks, stopping the evening commute, so they could search the area for evidence.

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No one was hurt.

Detectives from the Transit and Concord Police later identified two teen boys from Concord, ages 14 and 15, as the suspects.

Both will be summoned into court for possession of incendiary devices and interfering with public transportation.

Trains were cleared to go through the area by 7 p.m.

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Normal service is expected Wednesday morning.