In a tradition to honor the dead, priests will begin a process known as Akhand Path, a reading of the entire Sikh holy book, which is expected to take about 48 hours, the BBC reported.
"We want to pay homage to the spirits who are still in there," Harpreet Singh, the nephew of one of the victims, told the BBC.
As visitors -- including several police officers -- moved toward the seats, passing six caskets, a projection screen showed photos of those killed after a gunman opened fire at the Oak Creek Sikh temple.
On Thursday, Sikhs were allowed to return to their temple for the first time since the shootings. Members have spent the last day painting walls and replacing blood-stained carpet. After the memorial service in the gymnasium, they plan to return to the temple.
Religious leaders and parishioners keep searching for answers following the Sunday tragedy. FBI Special Agent in Charge Teresa Carlson said during a Wednesday news conference that investigators have not yet "clearly defined a motive."
Wade Michael Page was identified Monday by authorities as the sole shooter at the temple. Authorities said the 40-year-old former Army sergeant and white supremacist entered the gurdwara armed with a 9mm semiautomatic handgun. The FBI said Page died of a self-inflicted gunshot wound to the head after he was shot by police.
The temple's leader told NBCChicago.com he hoped Indian-owned businesses around the world would close Friday in the victims' memory.
Congressman Paul Ryan is also expected to attend.
Intellpuke: You can read this article by NBC News Correspondent Becky Bratu in context here: usnews.nbcnews.com/_news/2012/08/10/13218028-hundreds-pay-respects-to-victims-killed-at-wisconsin-sikh-temple?lite
Reporting by Associated Press writers was used in this news article.