The powerful earthquake hit eastern Turkey Sunday 1:41 p.m. local time with an epicenter in the village of Tabanli, 10 miles from Van, according to the U.S. Geological Survey.
As many as 80 buildings collapsed in the town of Ercis, including a dormitory and 10 buildings in Van, the Turkish Red Crescent said. Some highways also caved in, CNN-Turk television reported.
Turkey's state-run television reported that 59 people were killed and hundreds were injured in Ercis. Twenty-five others were reported dead in Van and four people, including a child, died in the nearby province of Bitlis. It said at least nine people were pulled out of debris alive.
The worst damage hit Ercis, in the mountainous eastern province of Van, close to the Iranian border. The Turkish Red Crescent said its rescuers pulled several injured people out of that collapsed dormitory.
"There are so many dead. Several buildings have collapsed. There is too much destruction," Zulfikar Arapoglu, the mayor of Ercis, told NTV television. "We need urgent aid. We need medics."
Turkish scientists estimated that up to 1,000 people could already be dead, due to low housing standards in the area and the size and shallow nature of the quake.
"We are estimating a death toll between 500 and 1,000," Mustafa Erdik, head of the Kandilli observatory, told a televised news conference Sunday.
In Van, terrified residents spilled into the streets screaming. Rescue workers and residents scrambled, using only their hands and basic shovels, to save those who were trapped.
Turkey lies in one of the world's most active seismic zones and is crossed by numerous fault lines. Sunday's earthquake struck in the country's most earthquake-prone region, around Lake Van near the border with Iran.
U.S. scientists recorded eight aftershocks within three hours of the quake, including two with a magnitude of 5.6.
Officials said the quake was also felt in Salmas, Maku, Khoi and several other towns in northeastern Iran but no damage has been reported.
In 1999, two earthquakes with a magnitude of more than 7 struck northwestern Turkey, killing about 18,000 people.
More recently, a 6.0-magnitude quake in March 2010 killed 51 people in eastern Turkey, while in 2003, a 6.4-magnitude earthquake killed 177 people in the southeastern city of Bingol.
Turkey's worst earthquake in the last century came in 1939 in Erzincan, causing an estimated 160,000 deaths.
The Associated Press contributed to this report.