U.N. and Eritrean aid officials said Eritrea, a country of 4 million people in the Horn of Africa, was hovering on the edge of a humanitarian tragedy: The more than half million people escaping fighting in western Eritrea added to a drought crisis that already threatened 300,000 others.

Exhausted evacuees, mostly women and children, tumbled out of trucks Friday to stake out a patch of soil away from the rapidly advancing front, which lay about 60 miles to the east. One evacuee, 14-year-old Abdullah Ali, sat surrounded by 3,000 other uprooted Eritreans in a camp that has gone up overnight.

"I don't know where my parents are," the boy said.

The lightning Ethiopian offensive caught Eritreans by surprise, splitting families as they fled. Ali rushed home when Ethiopian warplanes roared over Akordat last weekend, but found no one there. He fled the town 35 miles north of Barentu, then boarded a bus evacuating panicked Eritreans.

"We were playing soccer when the Ethiopian planes started bombing. I left without my parents," said Metker Gebrhiwe, 15.

Ali and Metker are just two of the 550,000 Eritreans the state-run relief agency says have been forced from their homes by the onslaught of Ethiopian troops, artillery and warplanes that began May 12. The latest round of fighting over the 620-mile border began when Ethiopia retook a piece of disputed territory Eritrea had seized in May 1998.

In the Ethiopian capital, Addis Ababa, the government denied any intention of taking over recognized Eritrean territory. "Ethiopia had no designs on sovereign Eritrean territory in 1993, and it does not have such designs now," an official statement said, referring to the year of Eritrea's independence from Ethiopia after a 30-year guerrilla war.

By midday Friday, 15 trucks and buses brimming with fleeing Eritreans had already arrived at this 2-day-old camp stretched across a desolate, rocky swath of land 10 miles north of Keren. Naizei Woldenu, a regional aid official, said the camp would reach its 30,000 capacity within days.

With Ethiopian forces already in control of Barentu and Akordat, Keren - 50 miles north of the capital, Asmara - displayed all the trappings of a front-line city. Eritrean troops in camouflage streamed through the streets. The manager of the main hotel was said to have locked the doors and left. Account holders crushed at bank doors to withdraw their money to stock up on food, or to prepare to flee.

"The enemy could attack at any time," Ibrahim Osman said as he fought to hold his ground among the crowd gathered in front of the local branch of the Commercial Bank of Eritrea.

Goiton Berke arrived in Keren three weeks ago from Phoenix, Ariz., to visit his hometown. He ended up consoling his mother and sisters after his brother, an Eritrean soldier, was killed this week by an Ethiopian artillery round.

"We are scared to death. We don't know anything," Berke said.

On Friday, Ethiopian state television said Ethiopian aircraft had bombed a military training center in western Eritrea near the Sudanese border as Ethiopian troops consolidated their control over Barentu. Barentu had been an important command and control center for the Eritrean army.

There was no immediate comment from the Eritrean government on the latest bombing report. On Thursday, the Ethiopians said they hit targets near Eritrea's Red Sea port of Massawa.

In Keren on Friday, scores of dust-covered trucks spilling over with sandal-shod soldiers trundled through town, away from the front and toward Asmara. The troop trucks were interspersed with flatbed trucks carrying missile launchers, tanks, heavy artillery and mobile radar units. They were headed south toward a second front.

In the barren settlement camp in Zron, meanwhile, the new arrivals started to slowly piece together a routine, hoping their stay wouldn't be long. The able-bodied lined up to help unload trucks of wheat from the United States, dates from Saudi Arabia and milk powder from the Netherlands, while others washed clothes and stretched them over bushes to dry under the glaring sun.

"I don't know when, but I'll go home," 14-year-old Abdella Adris said as he joined the queue.