(JNS) Nearly three months after Israeli forces arrested Khader Adnan, the senior Palestinian Islamic Jihad operative has died in prison, following an 87-day hunger strike.

Reuters cited Israeli prison authorities who said Adnan, 45, “refused to undergo medical tests and receive medical treatment” and “was found unconscious in his cell” at Nitzan Prison in Ramle early Tuesday morning.

Efforts to resuscitate him were unsuccessful.

Around 6:30 a.m., sirens sounded in southern Israel.

“Three rockets were launched from Gaza towards Israeli territory. No interceptors were launched in accordance with policy,” the Israel Defense Forces tweeted.

A fourth projectile was fired just after, landing in an open area.

The Iron Dome missile defense system only fires interceptor missiles to down projectiles headed towards populated areas.

“The occupation [Israel] will pay the price for [Adnan’s] death,” which “will be a lesson for generations,” said PIJ in a statement. “We will not leave this path as long as Palestine remains under occupation.”

Hamas, which rules Gaza, described Adnan’s death as a “coldblooded execution by the Israeli security services,” and warned that “the Palestinian people will not let this crime pass by in silence.

“The path of revolution and resistance will escalate,” said the terror organization.

The IDF instructed residents of the South to stay close to shelter and was preparing for a possible escalation in Palestinian violence.

Palestinian Authority Prime Minister Mohammad Shtayyeh called Adnan’s death a “deliberate assassination.” Ramallah said it would lodge a complaint at the International Criminal Court.

In February, Israeli security forces detained Adnan in his hometown of Arrabe, near Jenin, on suspicion of involvement in terrorist activities.

Adnan, long accused of being a spokesperson for PIJ, has regularly been held in administrative detention over the past 15 years, and is known for having gone on several lengthy hunger strikes.