More than 30,000 people have fled their homes in the Democratic Republic of Congo (DRC) and crossed into neighbouring Uganda after a rebel group that had been hiding out in eastern Congo attacked a town.

Families streamed across a bridge over a river near the border, clutching belongings. Some carried firewood over their heads, many brought livestock and women held small babies.

Al Jazeera's Malcolm Webb, reporting from the Ugandan side of the border on Friday, said people were so desperate to escape that some ignored the bridge and waded through the river.

Who are the Allied Democratic Forces? The ADF was formed in the 1990's by Ugandan Muslims who felt sidelined by the government.

They staged several attacks on villages and towns, including a 1998 massacre of 80 students at a college in Kabarole.

A government offensive that ended in 2001 killed many ADF commanders.

Remnant fighters fled to the Democratic Republic of Congo, where they have continued to wage small-scale attacks.

“We heard rumours there were rebels coming but we did nothing," Evaketi Tibalumanya, a Congolese Refugee, told Al Jazeera, holding one of her nine children in her lap.

"Then they came by surprise at night. They caught a person and killed him. We escaped death because we ran away.”

The Ugandan military said the Allied Democratic Forces (ADF), a Ugandan rebel group that was driven across the border into the dense jungle of the DRC after a violent campaign in the late 1990s, overran the town of Kamangu on Thursday.

They briefly occupied it and, though they have since left, Ugandan military spokesman Paddy Ankunda said people are still crossing into Uganda for fear of the rebels. Ugandan troops have been sent to reinforce the border.

The ADF waged an insurgency against the Ugandan government in the late 1990s from bases in the Ruwenzori Mountains and across the frontier in eastern Congo. At its peak, it was blamed for a series of deadly blasts in the capital.

'No food, no shelter'

Recently carrying out only minor attacks on villages and units of DRC's army, the group had kept largely silent since the Ugandan government offensive against it in 2001.

Aid groups and the Ugandan government are struggling to cope with an influx that took them by surprise.

“People have no food, they have no shelter, they are sleeping in the open. The classrooms that have been provided by the government are not adequate enough to accommodate the huge number of people,” Richard Nsubuga of the Uganda Red Cross told Al Jazeera.

Ugandan soldiers kept a close watch on the refugees as they crossed the border and Paddy Ankunda, Uganda's military spokesman, told a news conference that the military was worried the rebels might join the influx disguised as refugees.

Ankunda also said the military feared the ADF could have gained attack skills from al-Shabab, the al-Qaeda-linked group operating in Somalia, that could be used inside Uganda.

Al-Shabab have carried out the attacks in Ugandan capital Kampala before to avenge Uganda's deployment of troops as part of an African Union peacekeeping force in Somalia.