A series of strong earthquakes struck a mountainous area in western China on Wednesday, killing at least 400 people and injuring more than 10,000.

The toll is expected to rise as rescuers work to pull out people trapped underneath the many collapsed buildings.

“It’s very soon after the earthquake and the affected area is remote,” reported Frank Falkenburg, Asia desk officer at Caritas Germany.

“Phone lines are down and the fact Qinghai is an autonomous region makes the gathering of information more difficult,” he added.

What was immediately known, however, is the need for shelter and medical supplies and staff.

According to reports, hospitals were overwhelmed Wednesday with many lacking even the most basic supplies. Doctors were also in short supply.

And with night time temperatures falling below freezing, thousands of tents, coats, and blankets were being rushed to the region by the provincial government.

Jinde Charities in China, an organization supported by Caritas Internationalis, is currently assessing the disaster through the local church with a view to sending staff to the region.

According to the U.S. Geological Survey, six temblors were recorded for the region in less than three hours, all but one registering 5.0 or higher. The largest quake recorded by the USGS was a magnitude-6.9 one. The China Earthquake Networks Center measured the largest quake's magnitude at 7.1.

The state-run Xinhua News Agency, citing a local publicity official, reported that more than 85 percent of houses had collapsed in Jiegu, a city about 20 miles (30 kilometers) from the epicenter.

The most affected area, Yushu county in the southern part of Qinghai province, near Tibet, has a population of about 100,000, mostly herders and farmers.