Senators fired a barrage of criticism Thursday at a Facebook executive over the social-networking giant’s handling of internal research on how its Instagram photo-sharing platform can harm teens.

The lawmakers accused Facebook of concealing the negative findings about Instagram and demanded a commitment from the company to make changes.

During testimony before a Senate commerce subcommittee, Antigone Davis, Facebook’s head of global safety, defended Instagram’s efforts to protect young people using its platform. She disputed the way a recent newspaper story describes what the research shows.

“We care deeply about the safety and security of the people on our platform,” Davis