The U.S. government on Tuesday announced a $20 million reward for information related to four senior members of the Islamic State group. The information is being sought under the State Department’s Rewards for Justice Program.

The State Department named the four members as Abd al-Rahman Mustafa al-Qaduli, Abu Mohammed al-Adnani, Tarkhan Tayumurazovich Batirashvili and Tariq Bin-al-Tahar Bin al Falih al-‘Awni al-Harzi. A reward of $5 million each has been offered for information on Adnani, who has been named as the group’s official spokesman, and Batirashvili.

“Al-Adnani is ISIL’s main conduit for the dissemination of official messages, including ISIL’s declaration of the creation of an Islamic Caliphate,” the State Department said in the statement. “Al-Adnani was one of the first foreign fighters to oppose Coalition Forces in Iraq before becoming ISIL’s spokesman.”

Qaduli and Harzi, meanwhile, attracted rewards of $7 million and $3 million, respectively.

Under the Rewards for Justice Program, the U.S. government has previously announced a $10 million reward for information on Abu Bakr al-Baghdadi, the self-proclaimed caliph of the caliphate created by ISIS in northern Syria and Iraq. The highest reward offered under the program is $25 million for information on Ayman al-Zawahiri, who has been the leader of al Qaeda since the death of Osama Bin Laden in 2011.

The latest announcement comes just days after an attack on a cartoon exhibit in Texas by gunmen allegedly allied to ISIS. While the group claimed responsibility for the shooting, calling it an operation carried out by “two soldiers of the caliphate,” counterterrorism experts have questioned whether ISIS was involved in the attack.