Several gunmen wearing suicide vests have attacked a national television and radio station in the eastern Afghan city of Jalalabad, police have told Al Jazeera.

The attackers, which carried AK-47s, entered Radio Television Afghanistan (RTA) on Wednesday and engaged in a gun battle with security forces.

Two of them detonated their vests and at least one - possibly two - remained at large, police said.

"So far, three people have been killed and nine wounded, including journalists," Al Jazeera's John Hendren, reporting from Afghanistan's capital, Kabul, said, adding that the number of casualties was expected to increase.

"The fight could go on for some time because this is in a central part of Jalalabad, right next to the provincial governor's office and a busy square," he added.

There was no immediate claim of responsibility for the attack.

Jalalabad is the capital of Afghanistan's Nangarhar province, on the eastern border with Pakistan.

PHOTO CAPTION

Afghan security forces arrive at the site of an attack in Jalalabad city, eastern Afghanistan May 17, 2017. REUTERS

Al-Jazeera