Authorities briefly shut down the entrance to the Rosslyn Metro station Thursday evening after one sick child vomited on platform, which prompted a large crowd of young people to run out of the station, officials said.

The incident happened just after 9 p.m. when about 200 or more youths entered the station in Arlington, said Dan Stessel, a Metro spokesman. One of the juveniles became ill, and immediately other children reacted, running from the station.

The rush of youths from the station forced authorities to respond, and they briefly shut down the entrances for about 10 minutes as they investigated, Stessel said. Nothing hazardous was found and the station reopened.

Rail service was not affected.