A religious ceremony was held Friday morning to honor victims of the deadly bombing earlier this week at the Erawan Shrine in Bangkok, the capital city of Thailand. At least 21 people were killed in the country's worst ever bombing Monday, that also injured over hundred people.

The multi-faith -- Buddhist, Islamic, Christian, Sikh and Hindu -- ceremony took place at Ratchaprasong intersection, close to the shrine. The ceremony was reportedly attended by several high-ranking government officials and diplomats. 

Meanwhile, Thailand's police chief insisted that officers are making "a lot of progress" in the hunt for the suspect.

"We still have no information on international terror groups and think that there is no link to international terrorism," police chief Somyot Pumpanmuang said Friday, according to Reuters, after attending the prayer ceremony. "What is clear is that it was intended to discredit the government, destroy confidence and make tourists scared and not travel to Thailand."

However, investigating authorities are yet to determine who carried out the attack. Thai authorities reportedly have few solid leads, other than a security camera video that has pinpointed the prime suspect, who was seen wearing a yellow T-shirt and carrying a backpack.

Two suspects of the bomb attack were cleared by the Thai police late Wednesday, hours after they turned themselves in. The two men -- a Chinese tourist and a Thai guide -- were suspected to be linked to the blast after they were seen in the security video standing in front of the prime suspect in the investigation.

Thailand national police spokesman Lt. Gen. Prawut Thavornsiri told the Associated Press that the two men are "definitely" no longer suspects.

Thai officials believe the prime suspect, who has been described as an unidentified "foreign" man, planted a bomb in a backpack at the Hindu shrine, one of Bangkok’s famous tourist attractions. Police released a sketch of the suspect and issued an arrest warrant against him Thursday. A bounty of 1 million baht ($28,104) has been offered for any information leading to the arrest of the suspect.