Spate of killings spreads fear in US capital

Two groups of tourists were robbed at gunpoint at the National Mall in Washington, hours after a police chief declared a crime emergency in the US capital in response to a spate of violence that included the killing of a British political activist.

The activist, Alan Senitt, was attacked in the Georgetown area on Sunday, his throat was slit and police say the attackers attempted to rape his companion. It was the 13th homicide in the city this month. Robberies are up 14 per cent, and armed assaults have jumped 18 per cent in the past 30 days.

The tourist-friendly National Mall, a grassy area lined by museums leading up to the Capitol, is under the jurisdiction of US Park Police rather than DC police. It is usually considered safe but the crimes against tourists have raised calls for a larger police presence.

On Wednesday, Park Police were looking for connections between the latest mall robberies and three similar incidents in the area in late May. There have been no arrests in any of those cases.

On Tuesday night, two women were robbed at gunpoint by two men dressed in all black, said US Park Police Sgt Scott Fear. About 15 minutes later, a family of four was robbed by suspects with the same description, he said.

Though no one was injured, Sgt Fear said there were similarities to three violent attacks at the National Mall in May. In one case, a 17-year-old girl was sexually assaulted.

"We try to prevent this from happening," Sgt Fear said. "We're going to reallocate our resources. We're going to see what improvements we can make."

The District of Columbia Police Chief, Charles Ramsey, declared a crime emergency after Mr Senitt, a volunteer for the potential presidential campaign of the former Virginia governor Mark R. Warner, was killed.

The declaration allows commanders more flexibility to adjust officers' schedules and reassign them to high-crime areas. Police are asking Mall visitors to "be our eyes and ears," Sgt Fear said. "We're going to ask them to be vigilant."