CLINT, Tex. — Women held in rooms without running water, sleeping bags set up on concrete and children left apart from their families: That was what Democratic lawmakers said they heard about on Monday as they toured two Texas border facilities.

Their emotional, and graphic, descriptions came on a day when ProPublica reported the existence of a secret Facebook group for current and former Border Patrol agents. Posts on the group’s page included jokes about migrants’ deaths, obscene GIFs and doctored images of Hispanic lawmakers, the report said. Some of the most offensive posts were directed at Representative Alexandria Ocasio-Cortez, Democrat of New York.

Monday’s visit to the border by more than a dozen members of Congress — including Ms. Ocasio-Cortez and Representative Veronica Escobar of Texas — was a specific focus of some of the abuse on Facebook, ProPublica reported. One post used vulgar language to encourage agents to “hurl a ‘burrito’” at the two women.

Ms. Ocasio-Cortez fired back at the group on Monday night in a series of tweets describing the visit. “These officers felt brazen in there,” she said, pointing out that members of the congressional delegation were asked to surrender their phones before the visit. “While mgmt was telling us it was a ‘secure facility’ where *members of Congress* had to check their phones, we caught officers trying to sneak photos, laughing.”