THE hunt for a sniper whose killing spree has been terrifying Washington was stepped up yesterday, with members of the Secret Service who normally protect the President and foreign embassies sent to guard schools and highways.

After the roving marksman switched his sights from adults to a 13-year-old boy, who became his eighth victim when he was shot outside his school on Monday, the Washington region awoke yesterday traumatised by fear, increasing the pressure on the police and FBI to make an arrest.

Yesterday, a $160,000 (£102,000) reward was offered for information leading to a conviction, as President Bush described the killings as cowardly and senseless.

All school sports were cancelled, with tens of thousands of pupils locked inside school buildings, having been delivered by parents and escorted inside by security guards. Shops were largely empty and helicopter patrols were increased across the region.

Many people said that the random nature of the attacks had left the American capital more anxious than after last year’s September 11 strikes on the Pentagon and subsequent anthrax mail deaths.

“September 11 opened our eyes to let us know that we’re vulnerable to a terrorist attack, but this random shooting, you can’t describe it,” Donzell Cockrell, a Washington postman, said. “Here, we can’t say what this guy’s purpose is.”

Vast numbers of people in areas where the gunman has struck are now reluctant to leave their homes. Trips to petrol stations are being postponed, thousands are shopping for groceries after dark and teachers at some schools have masked ground-floor windows with paper.

The FBI confirmed last night that its federal agents had greatly increased their role in the manhunt. Montgomery County Police Chief Charles Moose, in whose area six of the attacks have taken place, said that police had received 1,250 credible leads from 6,025 calls and that a police officer had been stationed at every school in Montgomery and Prince George’s County. What is most unsettling for investigators, who have called on psychological profilers, is that the sniper, who uses a .223 calibre rifle, does not fit any of the usual categories of multiple killers. While many have a grudge to settle and pick a particular group, often leaving clues because they want to get caught, this killer appears to be cool and cautious. He is the rarest form of spree killer: one who does it for fun.

The murderous spree began last Wednesday evening, when a 55-year-old man was killed in Montgomery County. Four people, aged 25 to 54 and from diverse ethnic backgrounds, were killed on Thursday morning in Montgomery.That night, a 72-year-old man was shot closer to central Washington and a 43-year-old woman was wounded near Fredericksburg, 80 miles south in Virginia, on Friday afternoon.

The killer did leave one clue near Monday’s shooting. Police found a bullet casing in woodland about 300ft from the school, from where they believe the sniper fired. The boy, who had parts of his stomach, pancreas and spleen removed, was in a critical but stable condition last night.

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