ISLAMABAD, Pakistan (AP) _ A powerful earthquake shook southwestern Pakistan for nearly one minute today, collapsing homes and killing at least 80 people. In northwestern Iran, another quake killed 100 and injured 250.

Iranian television reported the magnitude-5.5 quake hit the towns of Ardabil and Meshkinshahr, causing considerable damage.

In neighboring Pakistan, dozens of others were injured when their sun-baked mud dwellings caved in, government officials said.

The 7.3-magnitude quake struck at 2:08 a.m. (4:08 p.m. Thursday EST) near Quetta, about 400 miles southwest of Islamabad.

Sleepy, frightened residents fled to the relative safety of open areas.

``There was complete panic,'' said Shahzad Zulfikar, an area resident reached by telephone. ``It's cold here, but still people are afraid to go home. I have never felt such a violent shaking.''

Ambulance workers said they feared the death toll could surpass 100. They said as many as 60 might have died in Harnai, a village just 30 miles away from the quake's epicenter.

The U.S. Geological Survey in Golden, Colo., said the quake was centered 70 miles east-southeast of Quetta, a city of about 200,000 that is the capital of Pakistan's least populated province, Baluchistan. The dead and wounded lived in the remote outskirts of the city.

Officials at the only large hospital in Quetta expected the casualty rate to rise when victims from more remote regions of the province were brought into the city.

Most of the damage was in the Sibi area, where Harnai is located. The area is a vast plain and the population is scattered throughout hundreds of small villages.

At sunrise, authorities in Quetta were urging people to return to their homes. Most people, wrapped in woolen blankets and sleeping on the roadside, refused, fearful of further tremors.

Electricity was shut down briefly following the quake, but telephones and water supplies were unaffected.

Baluchistan Chief Minister Akhtar Mengal visited the site and ordered quick emergency relief to the victims.

Pakistan Television reported that roads to several small villages southeast of Quetta had been closed and that at least one road had caved in.