United Nations officers say that many of the weapons used to attack the road are hidden in civilian buildings here.
The United Nations officers who were present did not dispute this account.
Neither attack could be confirmed, and United Nations officers in the area said they knew of no attack.
A United Nations officer warned that such an offensive could cause thousands of casualties.
United Nations officers said they had counted 19, and more were turning up by the hour.
"In a cease-fire, under the cover of night, anything can happen," said one United Nations officer with a wink.
A top-level United Nations military officer said he had not heard of the investigation.
"But we felt we had to do something, or there would be no alternative to air strikes," the United Nations officer said.
United Nations military officers and relief workers have been forbidden to discuss the report.
Many United Nations officers feel that their troops are dangerously exposed.
