A powerful earthquake struck northwestern Turkey this evening, once again plunging the region into chaos and misery, just two days before President Clinton was to arrive for a summit of European leaders. Dozens of people were killed and hundreds more injured, according to government estimates.

The earthquake, which measured 7.2 on the Richter scale, downed buildings and sent thousands of frightened residents scrambling into the streets in Bolu province, a hilly region halfway between Istanbul and Ankara, the capital. The quake was centered in the town of Duzce, about 115 miles northwest of Ankara.

Bolu was one of eight northwestern provinces hit by an Aug. 17 earthquake quake which claimed more than 17,000 lives, and left hundreds of thousands homeless. That earthquake measured 7.4 on the Richter scale, and was spread over a huge region in Turkey's industrial heartland. This evening's quake, while nearly as powerful, appeared to be concentrated in a much smaller area.

Even so, the death toll was expected to rise. The prime minister's office said at least 34 people had been killed, while a Health Ministry official said more than 120 were dead. Private NTV television quoted doctors as saying that 1,000 people were injured in Duzce alone.

"We are face to face with a new disaster; may Allah prevent major loss of life," President Suleyman Demirel said.

With around 200 residents killed and only a handful of buildings destroyed, Bolu province had escaped the August earthquake relatively unscathed. But the first images broadcast on Turkish television from Duzce late tonight showed row upon row of crumpled buildings and hundreds of dazed survivors seeking their loved ones amid the rubble.

"We are hearing the screams of people under the rubble. Please, this is an urgent call for help. Aid should come as soon as possible," said Ugur Gur, the provincial police chief.

One woman fell to her knees and burst into tears as she picked her way to an older woman lying lifeless between a collapsed ceiling and a sofa. "Why did Allah do this to us?" she cried as others sought to console her. "Give me back my mother."

The earthquake struck just ahead of a visit by Clinton, who is scheduled to arrive in Ankara on Sunday for a two-day official visit before going to Istanbul for the Nov. 18-19 summit of the Organization for Security and Cooperation in Europe. The meeting will be attended by more than 50 other world leaders and U.N. Secretary General Kofi Annan.

On Tuesday, Clinton is scheduled to tour Izmit, which was at the epicenter of the August earthquake, and meet with survivors.

Asked tonight whether the earthquake would affect Clinton's visit or the summit program, Demirel said: "I don't think so." In Washington, White House officials also said that as of yet the president had no change of plans.

The earthquake was felt in Ankara, where terrified residents fled their homes. As the initial panic subsided, thousands of people flocked to local hospitals here to donate blood for victims. The temblor also rattled buildings and houses in Istanbul, and as far south as the Mediterranean resort of Antalya.

The quake struck at 6:57 p.m. (11:57 a.m. EST), sending thousands of terrified residents of Duzce into the streets in search of safety. Fires erupted across the town and continued to rage uncontrolled for hours because the local fire station had collapsed. Many people were hurt after leaping off the balconies and out of windows of their apartments.

Electricity and phone lines remained down hours after the earthquake struck, making it difficult to assess the full extent of the damage. A major highway linking the town to Istanbul--about 120 miles to the west--was severely damaged and closed to traffic, impeding rescue efforts.

A handful of doctors at the hospital in Duzce struggled to cope with the steady stream of wounded. They had to be treated in the garden because the hospital had been evacuated.

Panic in Duzce intensified during the night as powerful aftershocks continued to rock the town. Electricity poles shook and buildings swayed as television reporters sought to continue reporting live from the disaster zone.

In the neighboring town of Kaynasli, a man was seen shouting: "The press is here, where is the state?" The scene was a familiar one. The government faced a barrage of public criticism over its sluggish response to the Aug. 17 earthquake.

Anger is resurfacing among thousands left homeless from that quake who are still sheltered in flimsy tents despite government pledges to provide all-weather shelter.

But this evening, the government of Prime Minister Bulent Ecevit was swift to react. It sent thousands of army troops to the region, and scores of ambulances and military helicopters ferried the wounded to hospitals in Ankara, where the wail of sirens continued through the night.