Fire department sirens have sounded across the Argentine capital to honor 85 people who died 25 years ago in the nation's worst terrorist attack — the bombing of a Jewish center.

Argentine prosecutors blame Iranian officials for plotting the attack on the Argentine-Israelite Mutual Association and say the Lebanese Shiite group Hezbollah carried it out. But nobody has been convicted despite years of investigations.

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People hold up pictures of people who died during the bombing at the AMIA Jewish center that killed 85 people on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

Fire department sirens have sounded across the Argentine capital to honor 85 people who died 25 years ago in the nation's worst terrorist attack — the bombing of a Jewish center.

FILE - In this July 18, 1994 file photo, firefighters and rescue workers search through the rubble of the Buenos Aires Jewish Community center after a car bomb destroyed the building, killing 85 people. Argentina announced on Wednesday, July 17, 2019, that it is creating an anti-terrorism database ahead of the 25th anniversary of its worst terror attack. (AP PhotoAlejandro Pagni, File)

Prosecutor Alberto Nisman in 2015 accused former President Cristina Fernandez of helping cover up the case, which she denies. Nisman was found dead in his apartment days later.

A sign reading in Spanish "Memory and Justice" and the names of those who died during the bombing of the AMIA Jewish center that killed 85 people is displayed outside the site of the attack on the 25th anniversary of the bombing in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A sign reading in Spanish "Memory and Justice" and the names of those who died during the bombing of the AMIA Jewish center that killed 85 people is displayed outside the site of the attack on the 25th anniversary of the bombing in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man holds the Spanish message:  "Here they kill" on the 25 anniversary of the bombing of the AMIA Jewish center that killed 85 people in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man holds the Spanish message: "Here they kill" on the 25 anniversary of the bombing of the AMIA Jewish center that killed 85 people in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man stands amid pictures of victims of the bombing of the AMIA Jewish center that killed 85 people, on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man stands amid pictures of victims of the bombing of the AMIA Jewish center that killed 85 people, on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

Earlier attempts at prosecutions collapsed. Iran has refused to turn over the people who now face charges, and denies any involvement.

People hold up pictures of people who died during the bombing at the AMIA Jewish center that killed 85 people on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

People hold up pictures of people who died during the bombing at the AMIA Jewish center that killed 85 people on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

Prosecutor Alberto Nisman in 2015 accused former President Cristina Fernandez of helping cover up the case, which she denies. Nisman was found dead in his apartment days later.

U.S. Secretary of State Mike Pompeo is to attend a memorial service on Friday.

FILE - In this July 18, 1994 file photo, firefighters and rescue workers search through the rubble of the Buenos Aires Jewish Community center after a car bomb destroyed the building, killing 85 people. Argentina announced on Wednesday, July 17, 2019, that it is creating an anti-terrorism database ahead of the 25th anniversary of its worst terror attack. (AP PhotoAlejandro Pagni, File)

FILE - In this July 18, 1994 file photo, firefighters and rescue workers search through the rubble of the Buenos Aires Jewish Community center after a car bomb destroyed the building, killing 85 people. Argentina announced on Wednesday, July 17, 2019, that it is creating an anti-terrorism database ahead of the 25th anniversary of its worst terror attack. (AP PhotoAlejandro Pagni, File)

A sign reading in Spanish "Memory and Justice" and the names of those who died during the bombing of the AMIA Jewish center that killed 85 people is displayed outside the site of the attack on the 25th anniversary of the bombing in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A sign reading in Spanish "Memory and Justice" and the names of those who died during the bombing of the AMIA Jewish center that killed 85 people is displayed outside the site of the attack on the 25th anniversary of the bombing in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man holds the Spanish message:  "Here they kill" on the 25 anniversary of the bombing of the AMIA Jewish center that killed 85 people in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man holds the Spanish message: "Here they kill" on the 25 anniversary of the bombing of the AMIA Jewish center that killed 85 people in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man stands amid pictures of victims of the bombing of the AMIA Jewish center that killed 85 people, on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)

A man stands amid pictures of victims of the bombing of the AMIA Jewish center that killed 85 people, on the 25th anniversary of the attack in Buenos Aires, Argentina, Thursday, July 18, 2019. (AP PhotoNatacha Pisarenko)