Maryland Governor Larry Hogan criticised Baltimore's mayor on Tuesday for a slow response to the riots in the previous night where angry protesters looted shops and burned buildings.
Governor Hogan said he had called Mayor Stephanie Rawlings-Blake repeatedly on Monday but that she avoided requesting the National Guard until three hours after violence first erupted, following the funeral of a 25-year-old black man, Freddie Gray, who died in police custody on April 19 after his spine was injured during a police arrest one week ago.
"The mayor of Baltimore had the city of Baltimore police on the ground. Quite frankly, they were overwhelmed. All the rest of the [boots] on the ground came from us," the Republican governor said the day after declaring a state of emergency in the largely black city.
Governor said neighbouring Pennsylvania, New Jersey and the District of Columbia were sending in hundreds of law enforcement officers to assist stabilise the situation in Baltimore and that he aims to have 2,000 troops activated by the end of the day in the city.
Baltimore Mayor Rawlings-Blake, a black Democrat, imposed a one-week curfew starting on Tuesday but urged the security officials to respond protesters in a way that would not escalate into more violence.
"It's a very delicate balancing act, when we have to make sure that we're managing but not increasing and escalating the problem," Rawlings-Blake said.
In a similar situation, Ferguson police came under intense criticism last year for quickly adopting a militarised posture, responding to the protest after fatal shooting of an unarmed black teenager, Michael Brown, by a white police officer, Darren WIlson.