Fireworks ignited inside a CTA Red Line station tunnel sending some people running from the downtown station Tuesday night.
"It was minor," and nobody was injured in the incident, Gregory said.
Police responded to reports of an explosion at the station about 6:40 p.m., a Central District officer said. The explosion sent people running from the station, the officer said.
As of 7 p.m. no offender has been arrested for igniting the fireworks.
According to an unconfirmed report, the firework ignited inside the tunnel was an M-80, but police nor CTA could not confirm the report.