Rescue workers remove debris as they search for victims of earthquake in Bhaktapur near Kathmandu, Nepal. Image: Niranjan Shrestha, The Associated PressThe death toll for the Nepal earthquake that struck Saturday has surpassed 3,700, according to official counts. But that toll will continue to rise – partly because of aftershocks that pose dangers and delays for rescuers, according to the BBC and other reports.

The 7.8-magnitude quake struck on Saturday, causing avalanches, and massive devastation around the country’s capital, Kathmandu, where tent cities have sprung up.

But a 6.7-magnitude aftershock struck again on Sunday, causing additional damage – and slowing down the response of humanitarian organizations, according to the BBC and other media outlets. It was just one of about 100 aftershocks that have terrified the region since Saturday’s initial event.

Aftershocks pose additional threats as responders arrive at scenes of disaster, according to experts. Fires, landslides, chemical spills, and further structure collapses can result. In Nepal, it has caused avalanches and enough fallen buildings to force thousands to sleep outdoors. Rescuers themselves have been forced to seek refuge because of the continuing seismological activity.

Because there are constant power outages, services from hospitals to airports have been severely curtailed, according to on-the-ground reports. Aid organizations like Project HOPE are seeking to get their resources deployed in the country.

“We are actively reaching out to our corporate partners to source donated medicines and supplies for health facilities overwhelmed by the disaster,” said Scott Crawford, the director of humanitarian assistance at Project HOPE.

The situation is growing more serious by the hour, according to the international press. Water is becoming scarce, and the threat of disease is growing, according to international agencies. With people remaining outdoors for fear of aftershocks, and a shortage of vaccines, the threat of diarrhea and measles could prove deadly, experts told the BBC.

Fourteen international medical teams are on the way to Nepal, and as many as 15 search-and-rescue teams en route, according to the United Nations.

The aftershocks are likely to subside over the next few days. Seismological activity is expected to decrease exponentially in the days after a large quake, according to the U.S. Geological Survey.

However, activity is likely to continue. During the Haiti earthquake in January 2010, one of the biggest aftershocks came on the eighth day after the initial quake – and it significantly slowed down rescue efforts to find victims buried in the rubble of Port-au-Prince.