A demonstrator’s 1-month-old baby girl is dead after an officer desperately tried to save her life during a police shooting protest Saturday in Baltimore.

Police said in a facebook post that the baby’s mother was one of about 30 people who were protesting at the scene of Friday’s police-involved shooting of a knife-wielding man, who remains in critical condition.

According to witnesses, the mother took a break from protesting to feed her baby inside a pizza shop. Seconds later, she told a customer that her little girl had stopped breathing, according to witnesses.

Police said people approached an officer and told him a baby girl was not breathing inside the restaurant. Maj. Richard Gibson then performed CPR until paramedics arrived. The baby was declared dead at a nearby hospital, the Washington Times reports.

Community activist Duane (Shorty) Davis, a critic of Baltimore police in the wake of Freddie Gray’s 2015 death in police custody, recorded the video and in it, he commends Gibson for doing his best to save the child, the New York Daily News reports.

He told Gibson he “did what he had to do for real.”