Updated

Brutalized residents of a border town repeatedly attacked by Islamic extremists, who last week killed more than 300 people, say they are moving across the border to Cameroon because they cannot trust Nigeria's government and military to protect them.

Gamboru has been targeted by militants in four attacks in the past year. But the fury and destruction wrought by last Monday's attack was unprecedented: more than 1,000 shops, dozens of homes and 314 trucks and cars bombed and burned out, said the chairman of the local Gamboru-Ngala government, Bukar Mustapha.

Bodies still are being found a week later amid the mangled tin roofs that are all that remain of the marketplace and in the surrounding bush where people tried to flee the killers, he told visiting Borno state Gov. Kashim Shettima on Sunday.

The extremists also bombed the only bridge linking northeastern Borno to neighboring Chad and Cameroon, leaving a mess of concrete and twisted girders that now allows only light traffic. Lines of trucks ferrying goods are stuck on either side of the bridge.

Residents said they warned the military beforehand that they saw suspicious camps in nearby scrubland and suspected fighters of the Boko Haram terrorist network were preparing to attack. They suggested some soldiers are colluding with the extremists -- not the first time such allegations have been made.

"We have more reasons now to believe a possible conspiracy may not be ruled out in the last attack, because the troops earlier stationed in the town were withdrawn a few hours before the gunmen laid siege," a spokesman for the residents, Modu Bulama told an Associated Press reporter.

Bulama said the departing soldiers said they were being re-deployed along roads leading to Lake Chad to search for 276 schoolgirls abducted by militants of the Boko Haram terrorist network -- but he did not believe that.

National and international outrage at the Nigerian government and military's failure to rescue the girls abducted four weeks ago forced President Goodluck Jonathan to accept offers of help from the United States, Britain, France and China. On Sunday, he accepted an offer from Israel to send a team of counter-terrorist experts.

Jonathan said Sunday he was "very optimistic" that the girls will be rescued with the international help.

But experts warn it will be difficult since the area they are in is vast. Reports last week indicated some had been forced to marry their abductors and others may have been carried across borders into Chad and Cameroon.

In Gamboru, Gov. Shettima tried to reassure residents with promises that victims would get financial help and that his government would rebuild the market and compensate traders for burned goods.

"We, the entire community, have long concluded arrangements to leave Nigeria for Cameroon, where we believe our lives may be well protected and safe", said trader Zannah Yerima. He said three of his brothers were killed in last week's attack.

Resident spokesman Bulama said: "The latest incident proved that the federal government and its security forces have failed to protect our lives and properties. Now that the level of killings and destruction inflicted on us reached its peak, the only alternative for us is to take our entire families and seek permanent refuge in Cameroon."

Thousands have been killed in the 5-year-old Islamic uprising.