LONDON/WASHINGTON—Police in Britain have arrested seven people following a series of hacks by the Lapsus$ hacking group which targeted major firms including Okta Inc. and Microsoft Corp., City of London Police said on Thursday. San Francisco-based Okta Inc,. whose authentication services are used by some of the world’s biggest companies to provide access to their networks, said on Tuesday it had been hit by hackers and some customers may have been affected. “The City of London Police has been conducting an investigation with its partners into members of a hacking group,” Detective Inspector Michael O’Sullivan said in an emailed statement in response to a question about the Lapsus$ hacking group. The ransom-seeking gang had posted a series of screenshots of Okta’s internal communications on their Telegram channel late on Monday. “Seven people between the ages of 16 and 21 have been arrested in connection with this investigation and have all …