A doctor headed for morning prayers at a Houston mosque was ambushed by three masked men who shot and wounded him on Sunday, a day after a Muslim man was beaten outside a Florida mosque.

The victim of the Texas incident, Dr. Arslan Tajammul, an eye specialist in his 30s, was undergoing surgery and was expected to survive, according to Mustafaa Carroll, executive director of the Houston branch of the Council on American-Islamic Relations (CAIR).

The doctor had parked his car and was walking to the Madrasah Islamiah mosque for the day's first prayers when he was ambushed and shot twice at about 5:30 a.m. EST (0930 GMT), Carroll said. His three attackers fled on foot.

"Police said it was an attempted robbery so we're waiting to see what the investigation finds," Carroll said.

"It's a real strange occurrence because the mosque is in a poor neighborhood, and they were wearing masks, which could mean all kinds of things," Carroll said.

Some people who pray at the mosque have been sleeping overnight there in the final days of Ramadan, the Muslim holy month that ends next week, he said.

Houston police did not immediately respond to a request for information.

The shooting took place a day after a Muslim man was beaten outside a Florida mosque that had been attended by the gunman who killed 49 people at an Orlando nightclub.

The victim in that case was punched in the head and face outside the Fort Pierce Islamic Center just after 4 a.m. (0800 GMT) on Saturday, the St. Lucie County Sheriff's Office said.

Taylor Anthony Mazzanti, 25, was arrested in the attack and was charged with felony battery, the sheriff's office said.

No racially motivated comments were made to the suspect during the incident, said the sheriff's office, which added the case is under investigation.

The Florida branch of CAIR, however, said the attacker uttered racially offensive comments including "You Muslims need to get back to your country" before the assault.

The Islamic Center's imam had requested extra security following last month's mass shooting by Omar Mateen at the Orlando gay nightclub Pulse. Mateen had worshipped at the centre.