2 soldiers and 1 police officer were killed in the skirmishes although no civilians were injured by crossfire, a military source told Al-Masdar News.
Subsequently, the Philippine Army withdrew from most of the city on Tuesday morning, thereby making it the first city in southeast Asia to come under Islamic State control.
In addition, ISIS members have captured the main prison in Marawi and released over a hundred prisoners, many of whom are caliphate sympathisers and may join its ranks.
Dozens of military vehicles and weapons were also captured during the battle although no official confirmation on the events have been issued by Amaq Agency yet.
Pictures of ISIS fighters raising the notorious black flag in downtown Marawi:
In response, Filipino President Rodrigo Duterte declared martial law in Mindanao province while the provincial mayor called on the army to send reinforcements which are expected to arrive tomorrow for a coming counter-assault.
The Philippine Army still controls most army bases and government buildings inside Marawi and has set up checkpoints on its outskirts although ISIS controls most of the residential areas. For instance, the main hospital in the city remains under siege. Marawi is home to over 200,000 residents and is roughly the size of Raqqa in comparison.
Rodrigo Duterte is currently in Moscow, visiting Vladimir Putin.
Amaq Agency recently released a series of images depicting an ISIS training camp at an undisclosed location in southeast Asia, likely near the newly captured Marawi city.