It's not safe for them to be there. Most of the NGO people from Kabul went over the border to Peshawar, but many have now moved on from there. Before the air strikes, some of the NGOs were negotiating with the Taleban about returning to Afghanistan. The air strikes have rendered those negotiations a thing of the past. It is unlikely that Western aid workers will be going back in the foreseeable future.
Clearly things are very tense at the moment.
A spokesman for the Church Mission Society said that aid workers in Afghanistan had left the country. We also know that people of English heritage in Khartoum are keeping in touch with the embassy.