WASHINGTON — An emergency call for help went out from a Metro train while an attack was taking place. But there are discrepancies in accounts of the incident over exactly when police showed up.

Metro Transit Police say they received the call at about 3:45 p.m. on Thursday from a passenger on a Green Line train that was heading to Branch Avenue. The passenger who made the call, Robert Bean, told NBC Washington that a pregnant woman was physically attacking another passenger.

Bean says that it took six stops, about a half-hour, before police arrived. But Metro Transit Police say officers arrived at the Branch Avenue Metro station only 10 minutes after they received the call. Police are investigating to see how long the attack lasted.

Police have not yet released the suspect’s name but say she is 33-years-old.