MADRID, Spain (CNN) — As police engaged in a standoff with three suspected North African terrorists Saturday night in a Madrid suburb, an explosion shook the neighborhood.
A policeman was killed and six to nine other people were wounded, said a reporter from CNN partner station CNN+, who was on the scene.
The explosion occurred about 9 p.m. (2 p.m. ET). It was originally reported by state radio to be a “controlled explosion,” in which police first move everyone back before exploding a bomb they are unable to defuse, CNN+ reporter Oscar Diaz de Liano said.
Diaz reported that at 9:45 p.m., at least four ambulances arrived at the scene, in addition to others that were already there.
Antena 3 television reported that the suspects had threatened to blow up the four-story building in the southern Madrid suburb of Leganes, about 10 miles south of the capital.
The police were searching for suspects who may be linked to the Madrid commuter train bombings, the Spanish news media reported.
The Web site of a leading Spanish daily newspaper, El Mundo, reported that a number of police officers may have been among the wounded and that a field hospital had been erected on the site.
The manhunt began late Saturday in the Leganes suburb of Madrid.
Earlier reports from the scene said there was a shootout and the suspects subsequently holed up in the building, which contains about 40 apartments.
Two helicopters hovered over it and a large contingent of police surrounded it, Diaz said.
Diaz and other witnesses said many people had been evacuated from nearby buildings
Explosives discovered Friday on Spain’s high-speed rail tracks between Madrid and Seville were the same type and brand as those used in last month’s terror attacks on Madrid’s rail network, Spain’s interior minister said.
Angel Acebes said it was still too early to determine whether the unexploded bomb could be linked to the Moroccan extremist group with ties to al Qaeda that officials say is the prime suspect in the March 11 bombings.
That attack killed 190 people and wounded more than 1,800.
The bomb was discovered by a railway employee and the Civil Guard defused it.
On Saturday, Acebes said he could not confirm if the detonator from the bullet train bomb was the same as those used on March 11, but added “it is possible.”
Spain’s bullet train service resumed Saturday after the state rail system RENFE halted the high-speed trains on Friday, putting thousands of passengers on hold at the beginning of the week-long Easter holiday.
A RENFE official said the bullet trains had extra cars to accommodate the stranded passengers.
There has been no known claim of responsibility for the bullet train bomb.
Acebes said it was “premature” to blame it on Moroccan Islamic Combatant Group (GICM), which is the group Acebes named last week as the prime suspect in the Madrid commuter train bombings. The GICM is listed by the U.S. government as a terrorist group.
The bomb consisted of 12 kg (26 pounds) of explosives and a detonator attached to a 136-meter (446 foot) long cable, but it lacked an “initiator,” Acebes said.
It’s believed that the perpetrators fled before fully setting the bomb along the bullet train tracks in Toledo province about an hour south of Madrid, Acebes said.
The National Court in Madrid has charged 15 people, including 11 Moroccans, in connection with the Madrid train bombings. The court also has issued international arrest warrants for five Moroccans and a Tunisian, who are being sought.
From Friday until nearly daylight Saturday, Acebes said authorities conducted a “kilometer by kilometer” search of the Madrid to Seville bullet train route. He also said a “permanent” monitoring system was now in place for the tracks, staffed by members of the military, police, Civil Guard and RENFE security.
The type and brand used in the Madrid train bombings, authorities have said, was the Spanish-made Goma 2 Eco explosive. It is widely used in mining.
The only Spanish citizen charged in the Madrid train bombings is thought by authorities to have led a group of Moroccans to the explosives in Spain’s northern coal mining region, where he used to work.
The Madrid bombs — 10 bombs in backpacks placed on four trains in three stations — were detonated March 11 by cell phones attached to the explosives.