Baltimore erupted in violence on Monday as hundreds of rioters looted stores, burned buildings and injured at least 15 police officers after the funeral of a 25-year-old black man who had died after he was injured in police custody.

The riots broke out just a few blocks from the funeral of Freddie Gray and then spread through much of west Baltimore in the most violent US demonstrations since those in Ferguson, Missouri, last year.

Maryland Governor Larry Hogan declared a state of emergency and called in the National Guard to restore order. US Attorney General Loretta Lynch, in her first day on the job, said she will send US Justice Department officials to the city in coming days.