A man has opened fire on an arena floor at a Caribbean music festival, wounding at least four people, police say, and two women were injured as the crowd rushed to flee the shooting.

Several thousand people had gathered at the arena for a Fourth of July party at the Houston Caribbean Festival, which was supposed to run until around 5am, Houston Police spokesman Jodi Silva said.

Witnesses told police they saw a man open fire at 1.55am on Saturday on the floor of the arena, hitting four men, Silva said.

“Everybody was having a good time, until someone shot a firearm,” Silva said.

Immediately after the shots were heard, people panicked and began to flee, Silva said.

Two females were hurt as people rushed to exit, but Silva did not know the extent of their injuries. Silva said the shooting victims were taken to two different hospitals, and one man was in critical condition and not expected to survive.

No ages or identities for any of those hurt were available immediately.

The Houston Caribbean Festival is an annual event that takes place during the holiday week at different venues in the area.

The arena is accessible by a small two-lane road, which made it difficult for emergency crews to arrive as thousands of cars tried to leave.

The organiser of the festival had medical care personnel at the arena that gave first aid to the victims, Silva said. They were assisted by people at the party who had medical training.

Silva says about 30 off-duty policemen were at the festival to provide security but they were on the perimeter of the arena.