According to authorities, Matin Azizi-Yarand, 17, then a student at Plano West High School, planned the attack for last May after being inspired by ISIS.

PLANO, Texas — A Plano teen has pleaded guilty to plotting an ISIS-inspired attack at Stonebriar Centre mall in Frisco last year.

Matin Azizi-Yarand, 18, was sentenced to 20 years in prison for solicitation of capital murder and 10 years for terroristic threat, according to the Collin County Criminal District Attorney's office. The sentences will be served at the same time.

Watch the Collin County District Attorney's office's full news conference:

According to authorities, Azizi-Yarand, then 17 and a student at Plano West High School, planned the attack for last May after being inspired by ISIS.

Police arrested Azizi-Yarand at Plano West last May. At the time of his arrest, Azizi-Yarand sent more than $1,400 to others for the purchase of weapons and tactical gear.

He had been talking online with an undercover FBI confidential human source about his desire to either "make Hijrah [travel]," or to conduct a terroristic attack within the United States, authorities said.

Through several conversations online, it was uncovered that Azizi-Yarand wanted to act as a lone wolf. He wanted to wait until he was 18 to carry out this attack, so he could purchase a rifle himself, according to affidavits.

"I've only been reading ISIS magazine guides for performing operations and making bombs," Azizi-Yarand told the undercover federal agent, according to an affidavit.

Affidavits showed that throughout several other online conversations, Azizi-Yarand sent the agent various types of ISIS propaganda.

"I'd like to actually make a cop surrender and drop his gun, then douse him with gasoline and burn him ... record it," Azizi-Yarand said during talks about the mall shooting.