"It was extremely chaotic; there were so many people running or crawling, the injured crying out in pain," she said by satellite telephone from Tuzla. "It was just totally overwhelming, the sheer numbers ... Obviously there was a high level of emotion, some people were fairly hysterical, understandably."
An air-burst rocket, fired by the Bosnian Serbs at the UN-declared "safe area" after Nato's air strike on Thursday, exploded at a cross-roads in the Old Town crowded with cafes and people. It is a popular spot for teenagers to hang out. It was a warm evening and there is little else by way of entertainment.
Ms Coe, a Canadian nurse, was told that 80 per cent of the victims were aged between 14 and the early twenties. The youngest was two years old, the oldest 40. She and a colleague rushed to the scene to ferry the wounded to hospital and the bodies to the mortuary. With the horror of the experience in her voice, she said 38 people were critically wounded in the attack.
Bosnian television showed gruesome pictures of the dead and wounded. Two men were seen struggling to carry the decapitated body of a young woman into an ambulance. Hospital workers were seen trying to save the wounded.
"The response was very impressive,'' Ms Coe said. ''There were dozens of cars, ambulances, people picking people up and getting them to hospital however they could.
"There was screaming. A lot of screaming,'' she added. ''Some were hysterical. It's mind-blowing, that amount of death."
Two aid workers from the office of the UN High Commissioner for Refugees were sitting only 50m from the blast, which is probably the bloodiest single attack of the war. "They said there was an explosion, two seconds of silence, then screaming and panic," said Kris Janowski, a spokesman for UNHCR in Sarajevo. "A lot of the victims have not been identified. Among the dead there were 10 children under 10."
The air raid siren sounded just after 7pm, when the first shell hit near by, "but then everything went quiet", Ms Coe explained. "It's like Sarajevo, that thing goes on all the time, and people have to get on with their lives."
Yesterday Tuzla was quiet but tense, with few people on the streets. Schools and businesses were closed. "Only a few essential shops are open," Ms Coe said. "People are in shock. Nothing like this has ever happened in Tuzla. Everyone is hanging on the radio and television, which are giving updates and the names of the injured."
Perhaps the Bosnian government should have predicted the Serbs' response.
"It was just a beautiful evening, so warm, and the place was just so full. That's the noted spot," Ms Coe said.
The Bosnian Vice President, Ejup Ganic, announced that today would be a national day of mourning for those killed.
But Ms Coe said: "Tuzla is already in mourning. Everyone is very downcast, sad, lots of tears. The city is grieving."