Gangster Vikas Dubey, wanted in connection with the Kanpur ambush in which eight policemen were killed, was on Thursday arrested at Ujjain in Madhya Pradesh, an official said. Eight policemen, including a deputy superintendent of police, were ambushed in Bikru village in the Chaubeypur area of Kanpur, where they had gone to arrest Vikas Dubey and fell to bullets fired from rooftops last Friday.