Thai officials have issued an arrest warrant for a foreign man wanted in the bombing that killed at least 22 people Monday at a shrine in Bangkok.

Thailand’s national police chief said Wednesday the suspected bomber was likely acting as part of a network. But, investigators have not yet been able to identify his motives or nationality.

Officials released a drawing of the suspect. He is a young man with black hair and round glasses. Authorities in Thailand are offering a $28,000 reward for information leading to the suspect.

Video from a security camera shows a young man with a yellow shirt leave a bag under a bench and walk away just before the blast.

A police spokesman said two other men in the video, one wearing red and another wearing white, are also suspects in the attacks.