German police on Friday arrested two terror suspects who had boarded a plane at Cologne-Bonn Airport, in a week that had brought a terror scare to Germany.

Two officers from Germany's State Criminal Office LKA shortly before 7 a.m. entered the KLM plane bound for Amsterdam. They were looking for a 23-year-old Somali and a 24-year-old German of Somali origin, identified by German daily newspaper Bild as Abdirazak B. and Omar D. Both men, who are living in the western state of North Rhine-Westphalia, were arrested and taken off the plane, officials said. Police ordered the remaining passengers, roughly 40, to leave the plane to identify their luggage. The KLM plane took off an hour late, landing safely at Schiphol airport in Amsterdam.

German police for months had surveyed the terror suspects. The arrest came after police found farewell letters stating that both would lend their lives to "jihad and possible terror attacks," a spokesman for the LKA told German news channel N24. The pair did not plan to hijack the plane, he added.

Bild said the two planned to travel to Pakistan via Amsterdam and Uganda to receive training in a camp of the terror group Islamic Jihad Union.

The IJU also trained a group of German terrorists who were arrested in 2007 in a major police operation; the so-called Sauerland group had amassed large amounts of explosives to bomb U.S. and other targets in Germany.

The latest arrest in Cologne comes just days after Germany's federal police alerted border authorities across the country to be on the lookout for Eric Breininger, a 21-year-old terror suspect who has been hiding in Pakistan recently.

Breininger is one of Germany's most wanted men. He had loose contacts with the two men arrested Friday, and very close ties to the Sauerland group snatched in 2007. The ringleader of the group, Daniel Schneider, is like an older brother to Breininger, police said. Breininger, who converted to Islam in February 2007, had surprisingly left the country two days before the Sauerland group was arrested.

Germany's federal police believe Breininger and his accomplice Hussein al Mallah are trying to enter Germany to launch terrorist attacks. They already have tried to buy explosives in Turkey, Guido Steinberg, a terrorism expert at the Institute for International and Security Affairs, a Berlin-based think tank, told German news channel N24.

The terror pair was last seen in Bosnia, roughly a week ago, although the online version of German newsmagazine Stern, citing intelligence sources, said Friday the pair already had entered Germany.

No matter their location, they are extremely dangerous: A few months ago Breininger appeared in a video clip showing off a Kalashnikov rifle, declaring he was ready to die in the name of jihad.

This week has brought a terror scare to Germany, with another incident in Cologne worrying the public.

On Tuesday three German teenagers of Turkish origin lured two police officers into a side road near a forest with the intent to steal their pistols and kill them, Bild said. They had planned to attack U.S. institutions in Germany -- and for that, they needed weapons. The police were able to overpower and arrest them. They have been charged with attempted murder.

Officials have been unwilling to link the case to any of the others, but the incident underscores Germany's precarious security situation.

Interior Minister Wolfgang Schaeuble in the past has admitted that Germany has become a target of terrorists because of the country's ongoing military contribution in Afghanistan.

Germany has roughly 3,500 soldiers in the Asian country, tasked mainly with reconstruction efforts in northern Afghanistan. It also has a squadron of Tornado jets that fly reconnaissance missions all over the country. Over the past year terror attacks on German soldiers in Afghanistan have become much more frequent.

At home, the Sauerland group had planned to hit targets in Germany right before lawmakers were due to extend the mandate (they have to do so every year in October) for the Afghanistan mission.

This year Germany plans a troop surge of 1,000, and observers say terrorists are trying to influence the parliamentary vote to end Germany's contribution in Afghanistan.

"If Breininger and Mallah are on their way to Germany, then that's no coincidence, then it's connected to the extension of the (Afghanistan) mandate," said Steinberg, the terrorism expert.

He added that because of the indoctrination by Islamist Web sites, sleeper cells have been formed all over Germany.

While he said these cells couldn't possible plan plots as grand as the attacks of Sept. 11, 2001, they are able to "attack soft targets, such as trains or subways," all over Germany.