TEHRAN, Iran (AP) — Iran said Tuesday that authorities have made arrests for the accidental shootdown of a Ukrainian passenger plane, which killed all 176 people on board and set off protests in the country demanding accountability after officials initially concealed the cause of the crash.

Iran’s Judiciary spokesman Gholamhossein Esmaili said “some individuals” were arrested after “extensive investigations.” His statement on the judiciary’s website did not say how many people had been detained or name those arrested.

Iran at first dismissed allegations that a missile had brought down the plane, but in the face of mounting evidence officials acknowledged on Saturday — three days after — that its Revolutionary Guard had shot down the plane by mistake as the force braced for a possible military confrontation with the United States.

The plane, en route from Tehran to the Ukrainian capital of Kyiv, was carrying 167 passengers and nine crew members from several countries, including 82 Iranians and 57 Canadians, many of whom were Iranians with dual citizenship. There were several children among the passengers, including an infant.

Iran’s president on Tuesday called for a special court with “a ranking judge and dozens of experts” to be set up to probe the incident.

“The responsibility falls on more than just one person,” President Hassan Rouhani said in a televised speech, adding that those found culpable “should be punished.”

“There are others, too, and I want that this issue is expressed honestly,” he said, without elaborating.

Rouhani called the incident “a painful and unforgivable” mistake and promised that his administration would pursue the case “by all means.”

“This is not an ordinary case. The entire the world will be watching this court,” he said.

Tensions have been escalating since President Donald Trump pulled the U.S. out of Iran’s 2015 nuclear deal with world powers, then reimposed sanctions that had been lifted under the accord.

The deal has quickly unraveled since then, with Iran steadily breaking away from limits on its nuclear program and Europe unable to find ways to keep Tehran committed.

The U.S. sanctions have devastated Iran’s economy.

On Tuesday, Britain, France and Germany triggered the so-called “dispute mechanism” action that paves way for possible further sanctions in response to Iran’s moves.