MERCED COUNTY (CBS SF) – A frightening chartered bus fire with school children aboard in the southbound lanes of I-5 shut down part of the interstate in Merced County for a time late Wednesday afternoon, according to authorities.

CHP reported the fire shortly before 4:30 p.m. near the city of Los Banos.

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While there was no word yet regarding where the bus or school children were from, video showed the smoky scene along the side of the freeway, where the bus fire had lit the grass off the shoulder on fire.

While initial reports indicated all the children got off the bus safely, medical assistance was called for one child who had an asthma attack on the side of the road.

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Another video of the scene showed a firefighting air tanker swooping down over the interstate, executing a water drop to put out the resulting grass fire.

Though the fire was put out by about 5:30 p.m., southbound traffic was still backing up on I-5 due to the closure of the right lane of the freeway. As of 6:30 p.m., there was still a massive traffic jam heading south.

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There was still no word as of early Wednesday evening as to the cause of the fire.