Scenes of chaos at a Cairo field hospital after at least 15 people were killed near the building where Egypt's deposed president Mohamed Mursi is being held.

Medical sources say the victims were Mursi supporters and included some children.

His backers, the Muslim Brotherhood said at least 37 were killed.

The Egyptian military said a 'terrorist group' had tried to storm the building and that one army officer was killed and 40 others wounded.

But some of those undergoing hospital treatment said soldiers and police had opened fire.

(SOUNDBITE)(Arabic) UNIDENTIFIED WOUNDED MAN SAYING:

"The people who were firing the most were the military. The police were also firing but the military were firing more. We've been betrayed as though it's the military of the Jews. I saw them with my own eyes."

There were more clashes on Sunday as rival supporters and opponents of Egypt's ousted president turned out in their thousands in Alexandria.

There were