OAK CREEK, Wis. — At least six people were killed Sunday when a gunman opened fire at a Sikh temple near Milwaukee, authorities said. The suspected shooter later died in an exchange of gunfire with police.

Police were called to the Sikh Temple of Wisconsin in the suburb of Oak Creek on Sunday morning, Aug. 5, when witnesses said several dozen people were gathering for a service.

Greenfield Police Chief Bradley Wentlandt said the first officer to arrive encountered a man police believe was the shooter. The two exchanged gunfire, and the suspect was killed, he said.

Wentlandt said police do not believe a second shooter was involved. He said tactical units went through the temple. They found four people dead inside and three outside the building, including the suspected shooter, he said.

It’s unclear how many others were wounded. Wentlandt said he had been told the officer who exchanged gunfire with the suspect and another person had been taken to hospitals. He said the officer was shot multiple times and is in surgery.

A Milwaukee level-one trauma center was treating the police officer and two other shooting victims. All are in critical condition, said Froederdt Hospital Chief Medical Officer Lee Biblo did not immediately identify the police officer but said the two other victims are men.

Hospital spokeswoman Carolyn Bellin said one of the victims suffered gunshot wounds to the face and extremities, and another had wounds to his abdomen. She did not know which was the police officer, or the nature of the third victim’s wounds.

Police said earlier that the officer is expected to survive.

Bellin said the hospital was not expecting any more shooting victims.

Sukhwindar Nagr of Racine, said he called his brother-in-law’s phone and a priest at the temple answered and told him that his brother-in-law had been shot, along with three priests. The priest also said women and children were hiding in closets in the temple, Nagr said.

Sikh rights groups have reported a rise in bias attacks since the Sept. 11, 2001, terrorist attacks. The Washington-based Sikh Coalition has reported more than 700 incidents in the United States since 9/11, which advocates blame on anti-Islamic sentiment. Sikhs don’t practice the same religion as Muslims, but their long beards and turbans often cause them to be mistaken for Muslims, advocates say.

Sikhism is a monotheistic faith founded in South Asia more than 500 years ago. It has roughly 27 million followers worldwide. Observant Sikhs do not cut their hair; male followers often cover their heads with turbans — which are considered sacred — and refrain from shaving their beards.

Roughly 500,000 Sikhs live in the U.S., according to estimates. The majority worldwide live in India.