Baltimore erupted in violence as hundreds of rioters looted stores, burned buildings and at least 15 police officers were injured following the funeral of a 25-year-old black man who died after suffering a spinal injury in police custody.

The riots broke out blocks from where the funeral of Freddie Gray took place and spread through much of west Baltimore.

It was the most violent protest against police treatment of African Americans since riots in Ferguson, Missouri, last year.

A state of emergency was declared by Maryland Governor Larry Hogan, a Republican, who sent in the National Guard, and a curfew was imposed in the majority black city from Tuesday night, with exceptions for work and medical emergencies.

Firefighters battled numerous blazes through Monday night, including one that consumed a church's senior center under construction in East Baltimore. Police said looting, fires and attacks against officers continued overnight.