HOUSTON: A Muslim doctor headed for morning prayers on Sunday at a Houston mosque was shot in an attack by three men, police said. The motive for the attack was unclear, but comes a day after another 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 wounded physician escaped internal organ damage and was expected to fully recover, though he remained hospitalised in intensive care late on Sunday, according to Houston police officer Muzaffar Siddiqi, a liaison with the city's Muslim community.

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

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

Siddiqi said investigators had not confirmed the assailants were masked. He urged the public not to jump to conclusions, despite concerns in the Muslim community that the attack was a hate crime.

"We don't know yet," Siddiqi told Reuters in a telephone interview, adding that robbery might have been the motive. But he said police were escalating their presence around the mosque in the meantime. The Muslim holy month of Ramazan ends on Tuesday.

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 Centre early 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, adding that the case was still under investigation.

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

The Islamic Centre'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.