A bomb exploded Thursday afternoon in a suitcase near the El Al Israel Airlines check-in counter in Madrid's Barajas Airport, injuring 13 people, police said.
Seconds before the blast, an El Al security officer saw smoke coming out of the suitcase and stopped the conveyor belt that was carrying it to the cargo area, police said.
Then the bomb exploded, blowing a hole in the ceiling, ripping off doors and sending passengers fleeing in panic. Airline counters in a 100-yard radius were damaged.
Police said the suitcase belonged to the last passenger to check in for El Al's non-stop Flight 396 to Tel Aviv. A police spokesman said that the passenger was arrested and was being questioned, but he refused to disclose the suspect's name or nationality.
No group immediately claimed responsibility for the bomb, which exploded one hour after Israel's ambassador to Spain, Samuel Haddas, arrived in Madrid on an El Al flight from Tel Aviv.
Airport director Domingo Perez said the arrested suspect had "aroused suspicions" at the counter, prompting El Al security personnel to watch his luggage. Perez said the suspect, initially described as being of Arab appearance, carried a Spanish passport, but a police source expressed doubt about the validity of the passport.
Five people were treated at the airport for minor cuts and bruises. Five others were treated and released from a local hospital. Three people were admitted to the hospital with more serious injuries.
One of those treated at the airport, Carlos Lozano, told reporters: "I was reading a paper when I saw the El Al guy with a fire extinguisher running towards a suitcase that had smoke coming out of it.
"Then I heard a big explosion, glass broke all over and the ceiling started falling in."
Lozano, an Argentine, said he was waiting for a flight to Buenos Aires.
Flight 396 was delayed indefinitely as Spanish civil guardsmen examined the Boeing 767 aircraft for any additional explosives. However, the airport information service said all other flights were leaving on schedule.
El Al said 96 people were on the passenger list for Flight 396. El Al and Iberia Airlines, the Spanish carrier, operate five flights a week between Madrid and Tel Aviv, several of them via Barcelona.
Security at Barajas and Barcelona's El Prat Airport was increased last January after Spain opened diplomatic relations with Israel. Passengers boarding El Al and Trans World Airlines flights in Madrid and Barcelona are subjected to thorough searches and are questioned by security personnel.
The bombing was believed to be the most serious terrorist attack since the U.S. bombing of Libya on April 15. The U.S.