(3rd UPDATE) Eight civilians on Sunday were found dead in a ditch approaching Marawi City, where state forces are battling Maute fighters.
Authorities discovered the bodies of the eight men after following a trail of blood on a road leading to the city at around 8 a.m.
The victims had their hands tied and bore gunshot wounds on their heads. Beside them was a cardboard sign with the word "Munafik," which means traitor or liar, as well as several empty gun shells.
Residents surmised that Maute fighters were behind the murder, and that the rebels may have suspected the victims to be government informants.
However, two female residents identified the victims as workers of a local bakery. The workers were allegedly stopped by Maute fighters as they were fleeing to nearby Iligan City.
The extremists allegedly separated the Christians from their Muslim companions, the women claimed.
A man, who requested not to identified, said he and the victims were among 19 men held by Maute fighters yesterday.
The extremists allegedly ordered them to recite Muslim prayers, and those who couldn't were taken away.
Another batch of eight civilians -- including four men, three women and a child -- was found dead near a university in Marawi after a few hours.
Authorities said the militants had killed a total 19 civilians in Marawi, a mostly Muslim-populated city of 200,000 people. These included three women and a child who were found dead near a university.
Thirteen soldiers, two policemen and 51 militants have died in the fighting, according to authorities. This brings the combined official death toll to at least 85.
The violence began when dozens of gunmen went on a rampage throughout Marawi after security forces attempted to arrest Abu Sayyaf leader Isnilon Hapilon. -- With reports from Agence France-Presse; Ron Gagalac, ABS-CBN News