(CNN) -- A suicide bombing killed at least 25 people Wednesday in the Palace of Justice, the main courthouse in Damascus, Syrian state TV reports, citing police.

A number of people were wounded in the attack, which occurred during work hours. The Syrian prosecutor general said the strike was timed to inflict many casualties

Police tried to prevent the attacker from entering, but he was able to force his way into the location and blew himself up.

There was no immediate claim of responsibility.

Over the weekend two bombings in Damascus targeting buses of Iraqi pilgrims killed more than 70 people. An umbrella group of Syrian Islamist rebels claimed responsibility.

Since the Syrian conflict began in 2011, an estimated 400,000 Syrians have been killed in what the United Nations is calling the worst humanitarian crisis since World War II.