A Texas man was arrested Friday on charges that he sent more than a dozen threatening messages to San Antonio’s mayor over two days, leading the mayor’s staff to believe the man could be “the next mass shooter,” according to a warrant affidavit.

Adam Thomas Converse, 25, is facing charges of making a terroristic threat to a public servant and resisting arrest, the San Antonio Express-News reported.

According to a warrant affidavit cited by the paper, Converse sent at least 14 threatening messages to San Antonio Mayor Ron Nirenberg through Facebook Messenger on Oct. 4 and Oct. 5.