Humanitarian crisis in Syria is worsening, 'horrified' U.N. official warns

Stephen O'Brien spoke to reporters at the end of a three-day visit to Syria.

"I am absolutely horrified by the total disregard for civilian life by all parties in this conflict," he said. "Attacks on civilians are unlawful, unacceptable and must stop. I appeal to every party engaged in violence and fighting to protect civilians and to respect international humanitarian law."

Syria has been locked in a civil war since 2011. At least 250,000 Syrians have been killed, more than a million injured, and almost half of the population have been displaced, according to O'Brien.

Just Sunday, airstrikes from government forces hit the rebel-held town of Douma, killing as many as 82 people and wounding hundreds, the Syrian Observatory for Human Rights and aid groups reported. Activists said at least 250 people were wounded.

Graphic video purporting to show the immediate aftermath of the blast depicted huge plumes of smoke, bodies strewn on the street and people frantically running for their lives.

Warning that the conflict in Syria undermines the security of the region and elsewhere, O'Brien called on the international community to give more.

He said that the humanitarian appeal for the year is less than 30% funded, some three-quarters of the way into 2015.

"It's vital that we say that this is unacceptable, and we've got to uphold humanitarian law," O'Brien told CNN.

"Equally, we have to give space for the political track because there is no military solution to this. There is not even a humanitarian solution. We can do our best to try and save the lives and protect the civilians, but almost anything we do is never going to be enough," he said.

(CNN)