COXS BAZAR, Bangladesh (Reuters) - More than 18,000 Rohingya Muslims , many sick and some with bullet wounds, have fled the worst violence to grip northwest Myanmar in at least five years, while thousands more are stuck at the Bangladesh border or scrambling to reach it.

Fridays series of coordinated attacks by Rohingya insurgents on security forces in the north of Myanmars Rakhine state and ensuing clashes triggered the Rohingya exodus, while the government evacuated thousands of Rakhine Buddhists.

Since the attacks, about 18,445 Rohingya - mostly women and children - have registered in Bangladesh, the International Organization for Migration (IOM) said on Wednesday.

They are in a very, very desperate condition, said Sanjukta Sahany, who runs the IOM office in the southern town of Coxs Bazar near the border.

The biggest needs are food, health services and they need shelter. They need at least some cover, some roofs over their heads.

Sahany said many crossed with bullet injuries and burn injuries, and that aid workers reported that some refugees gave a blank look when questioned.

People are traumatized, which is quite visible.