One onf Spain's top military officers, Lt. Gen. Emilio Villaescusa was kidnapped this morning by four gunmen in Madrid as he left his apartment house.

It was the second abduction of a high Spanish official in six weeks, and the government seemed clearly concerned that the new kidnaping would affect its demoratization process.

The incident - which sent shock-waves through the conservative Spanish armed forces hierarchy - coincided with the second fatality in two days of street violence in the capital. A 20-year-old woman student was killed this afternoon by a smoke bomb canister that struck her head during a demonstration to proteest the killing of a youth by two right-wing gunmen after a forbidden Sunday amnesty rally.

Protesters today shouted "amnesty" and "no more murders" as they clashed with police at Madrid University and in the heart of the city. A third student was reported in grave condition and undergoing surgery.

Gen. Villaescusa, 65, president of the supreme military tribunal, apparently was seized by the October 1 anti-fascist revolutionary group, GRAPO, a mysterious underground group that has inspired terror and confusion at the highest-government lovels.

On December 22 the group kidnaped Antonio Maria de Orioly Urquijo, president of the Council of State and the country's fourth-ranking official. The underground has held him ever since, and has eluded one of the biggest police hunts in recent Spanish history.

GRAPO demanded the release of nearly 200 prisoners jailed for political violence in exchange for Oriol, one of Spain's richest men. The government refused to deal with the underground but it promised to expand the amnesty granted last summer by King Juan Carlos when Oriol is released.

In a note to a Madrid newspaper last week, the guerillas warned that unless the government acted to free the political prisoners it would strike again.

Gen Villascusa was apparently kidnaped to show the government that GRAPO was serious. The organization, claimed responsibility in a telephone call to the Madrid daily Diario 16.

The general was taken by two young men who had been waiting in a car parked outside the apartment house where the former army chief of staff, who suffers from a heart ailment, lives with his wife and son. Two men forced the general into his limousine at gunpoint. The gunmen were covered by two others in military dress in a second car.

Villaescusa was pushed into his own flag-bedecked official car and driven away. The bogus escort followed. The limousine was found later in an industrial suburb, with the driver bound and gagged, locked inside. Eyewitnesses told police the Villaescusa had been transferred to a battered automobile.

Alerted minutes after the abduction, police set up roadblocks along all roads leading out of the capital and ordered close control of the borders with France and Portugal.

Premier Adolfo Suarez held an emergency meeting with the military vice premier, Lt. General Manuel Guiterrez Mellado, and with Interior Minister Rodolfo Martin Villa. The premier kept in close touch with the king, who returned from a skiing trip last last night.

The kidnapping bore a close resemblance to that of Oriol. Th guerrillas simply sped the general through Madrid's streets and vanished.

The general's family announced tha he was ill and required special medication for his heart at regular intervals.