On Wednesday morning, a Red Cross staffer in Afghanistan pushed his vehicle's panic button.

Three Red Cross vehicles were heading to meet up with a convoy of trucks carrying "winter feed" — food for livestock — in the remote northern province of Jowzjan in Afghanistan. The plan was for the Red Cross staff to help distribute the 1,000 tons of feed, which is critical for farmers. In the winter, there's nowhere for their animals to graze.

Before the vehicles got to the distribution point, they were ambushed by armed men. The panic button sent an alert to Red Cross offices in Kabul, but efforts to reach the staffers by satellite phone and other means failed. "We couldn't get hold of them," says Thomas Glass, head of communications for the International Committee of the Red Cross in Afghanistan.

Eventually, community elders, who keep in touch with the Red Cross office in Kabul, reported what little information they had. Six Afghan nationals were shot and killed — the driver of each vehicle and field staff accompanying them. Two additional field staff are missing; the Red Cross is "desperately" searching for them, says Glass.

To learn more, we spoke to Glass, age 37, a Swiss national who'd worked in the country from 2010 to 2012 and returned to Kabul for his current tour of duty in October. This conversation has been edited for clarity and length.

What do you know about the attack?

It's extremely hard to have exact information. We don't know the number of men, we don't know the motives, we don't know who is behind this.

An Afghan official in the area said it was a group with ties to ISIS.

We actually don't know. We don't have confirmation.

Is there any chance this was just a random occurrence, that the attackers didn't realize they were attacking Red Cross vehicle?

The vehicles are clearly marked. This has all the signs of a deliberate attack.

Red Cross workers have been attacked before in Afghanistan. But the loss of 6 lives at one time seems like another level of violence.

It's definitely a step further. We have 30 years of continuous presence in Afghanistan. So we are well-known, we are respected for our work. To have such a despicable attack, it's shocking. We're completely devastated. We're having a hard time understanding why and how this happened.

How do you decide if it's safe to send out staff in an area where there's conflict?

We communicate with all parties in the conflict, all the weapon bearers. We notify them. We receive security guarantees. If it's not safe to go, we don't go. If it is deemed safe enough, we will try.

The Red Cross has a full plate in Afghanistan, supporting health care, anti-poverty work, sanitation efforts and much more. The ICRC has now issued a statement that activities are suspended until Tuesday — and possibly longer.

Certain activities, such as the treatment of patients at medical facilities, will continue. But any movement in the field, including the transfer of war-wounded to hospitals, is on hold.

Do you think the Red Cross might pull out of Afghanistan?

We have to regroup, to get a sense of what happened — and how to continue our work without jeopardizing the safety and security of our staff. It's clear that we're not leaving Afghanistan. We are here for the Afghan people. So many innocent people are trapped by this conflict. We can't leave them behind, that's for sure.

NPR experienced a loss in Afghanistan last year, when photographer David Gilkey and interpreter Zabihullah Tamanna were killed. And Afghanistan has the most attacks on aid workers per year — 101 attacks in 2015. What do you make of this?

It's not just in Afghanistan. War and conflict brings out the worst in people. And the work of humanitarian workers and journalists has become increasingly not just difficult but dangerous. We've seen more and more deliberate targeting of aid workers and journalists.

Does a tragedy like this make it hard to sleep?

These last few days have been so incredibly intense that as soon as my head hits the pillow I'm out. But I'm up at 4.

The six victims were Afghan nationals. What has the reaction been among Afghans?

What strikes me most is the resilience of the Afghans and the Afghan colleagues. This attack reinforces the belief that we need to continue our work, in the name of our deceased colleagues we need to persevere.

Is there any one interaction with an Afghan that stands out?

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