MADRID — Three lead defendants in the 2004 Madrid train bombings were found guilty of mass murder and other charges today but four other top suspects were convicted on lesser charges and an accused ringleader was completely acquitted.

The verdicts were a partial victory for prosecutors, with 21 of the 28 people on trial convicted on at least some charges. Seven got off entirely, including an Egyptian who prosecutors said had bragged that he masterminded the March 11, 2004 blasts, which killed 191 people and injured more than 1,800.

The three lead suspects convicted of murder and attempted murder each received sentences ranging from 34,000 to 43,000 years in prison, although under Spanish law the most time they can spend in jail is 40 years. Spain has no death penalty or life imprisonment.

The three are: Jamal Zougam, a Moroccan convicted of placing at least one bomb on one of the trains; Emilio Suarez Trashorras, a Spaniard who is a former miner found guilty of supplying the explosives used in the attacks; and Othman Gnaoui, a Moroccan accused of being a right-hand man of the plot’s operational chief.

Top suspects Youssef Belhadj, Hassan el Haski, Abdulmajid Bouchar, and Rafa Zouhier were acquitted of murder but convicted of lesser charges including belonging to a terrorist organization. They received sentences of between 10 and 18 years.

Fourteen other people were found guilty of lesser charges like belonging to a terrorist group.

Accused mastermind Rabei Osman, who is in jail in Italy, had allegedly bragged in a wiretapped phone conversation that the massacre was his idea. But his defense attorneys argued successfully that the tapes were mistranslated.

Six lesser suspects were acquitted on all charges in addition to Mr. Osman.

Much of the evidence against the men was circumstantial. Bouchar, for instance, had been seen on one of the bombed trains shortly before the attack, but at trial nobody could definitively identify him.

Circumstantial evidence is admissable in Spanish court but the judges may have avoided relying heavily upon it because of a number of high-profile terror cases that were overturned on appeal, including one involving a Spanish cell accused of involvement in the September 11 attacks.

Judge Javier Gomez Bermudez read out the verdicts in a hushed courtroom, with heavy security, including bomb-sniffing dogs and police helicopters, outside.

Prime Minister Zapatero, who came to power after the attacks, welcomed the verdicts. “Justice was rendered today,” he said.

“The barbarism perpetrated on March 11, 2004, has left a deep imprint of pain on our collective memory, an imprint that stays with us as a homage to the victims,” Mr. Zapatero said.

Most of the suspects are young Muslim men of North African origin who allegedly acted out of allegiance to Al Qaeda to avenge the presence of Spanish troops in Iraq and Afghanistan, although Spanish investigators say they did so without a direct order or financing from Osama bin Laden’s terror network.

Judge Bermudez said the probe had turned up no evidence of involvement by the armed Basque separatist group ETA, dismissing the initial argument of the conservative pro-American government in power at the time of the attacks. The theory is still embraced by many Spaniards.

The day of carnage is etched in Spain’s collective memory and became widely known as simply 11-M, much as the term 9-11 conjures up so much pain for Americans.

The sentences of thousands of years for lead suspects are largely symbolic because the maximum jail time for a terrorism conviction in Spain is 40 years. Spain has no death penalty or life imprisonment.

Seven suspected ringleaders of the attacks — including the operational chief and an ideologue — blew themselves up in a safe house outside Madrid three weeks after the massacre as special forces who tracked them via cell phone traffic moved in to arrest them.

The attacks had profound political repercussions and left Spaniards deeply and bitterly divided between supporters of conservatives in power at the time of the massacre and Socialists who accused the government of making Spain a target for Al Qaeda by supporting the Iraq war and sending in 1,300 peacekeepers.

The government of the prime minister at the time, Jose Maria Aznar, initially blamed Basque separatists for the bombings, even as evidence of Islamic involvement emerged.

This led to charges of a cover-up to deflect attention away from the government’s support for the war, and in elections three days after the bombings the conservatives lost to the opposition Socialists, who quickly brought the Spanish troops home.