(AP) -- A stunned German town mourned 16 students who went down aboard Germanwings Flight 9525 on their way home Tuesday from a Spanish exchange, while the opera world grieved for two singers who were returning from performing in Barcelona -- one of them with her baby.

"This is surely the blackest day in the history of our town," a visibly shaken Mayor Bodo Klimpel said after the western town of Haltern was shocked by news that 16 students from the local high school and two teachers had been on the plane. They had just spent a week in Spain.

Some hugged, cried and laid flowers in front of the Joseph Koenig High School, where the 10th graders had studied, and lit candles on its steps.

"This is pretty much the worst thing you can imagine," Klimpel said at a hastily called news conference.

An announcement was made to students Tuesday lunchtime that "that we were all free now but we shouldn't be happy," said Christopher Schweigmann, 16, a 10th-grade student who said he lost two good friends. Students went to a service Tuesday evening, and "everyone was in tears in the church," he said.

"It's impossible to believe that they all won't be there anymore in the coming days," he said.

Crisis counselors were at the school soon after the crash.

"I think many haven't really grasped what happened, and I think the grief will come a bit later for many," counselor Ingo Janzen said.

"The town is totally silent, nothing is happening anymore in town, everyone is like petrified," said resident Gerd Schwarz, 64.

The town of 38,000 lies about 80 kilometers (50 miles) northeast of the plane's destination, Duesseldorf.

Officials confirmed that the school group was among the 150 people on board the plane. Among the victims were also two opera singers, business travelers en route to a trade fair in Cologne and two babies.

A total of 67 Germans, many Spaniards, two Australians, and one person each from the Netherlands, Turkey, and Denmark were among the victims, according to their respective governments.

Spanish authorities were still trying to determine how many of their citizens were on board. The Mexican government said there were indications that one Mexican national was also among the victims.

The German students and their teachers spent a week in Llinars del Valles and were seen off at the town's train station early Tuesday by their Spanish host families, said Pere Grive, the deputy mayor of the town of 9,000, about a 45-minute drive from Barcelona.

German and Spanish students from the two towns have been doing such exchanges for at least 15 years. The Spanish students had spent time in Germany in December.

"We are completely shattered and the students are also devastated," Grive told The Associated Press.

In Haltern, the high school was going to be kept open Wednesday but no classes were planned.

"There will be an opportunity for the students to talk about the terrible event," Klimpel said.

Also among the passengers were two German singers who had been in Barcelona to perform in Richard Wagner's "Siegfried" at the city's Gran Teatre del Liceu -- Duesseldorf-born contralto Maria Radner and bass baritone Oleg Bryjak, who was born in Kazakhstan but had been a member since 1996 of the ensemble at Duesseldorf's Deutsche Oper am Rhein opera house.

"We have lost a great performer and a great person in Oleg Bryjak. We are stunned," said Christoph Meyer, director of Deutsche Oper am Rhein.

Radner took the Germanwings flight with her husband and baby, Liceu director of communications Joan Corbera said. He added that the theater's employees will hold two minutes of silence on Wednesday in the singers' honor.

Also traveling on the plane with her baby was Marina Bandres, who came from Jaca in the Spanish Pyrenees and lived in Britain, Jaca Mayor Victor Barrio said. Bandres had been attending a funeral in Jaca for a relative.

Business travelers included Carles Milla, the managing director for a small Spanish food machinery company, his office said, adding that he had been on his way to a food technology fair in Cologne. Two employees of Barcelona's trade fair organization were also on the flight.

Catalonia's regional leader, Artur Mas, said the government would arrange transportation for families who want to view the crash site but did not say when the visit would take place.

At Barcelona airport, passenger Marcel Hemmeldr said he felt "very strange" to check in for Germanwings' evening flight to Duesseldorf.

"The people were standing at the same place where we're standing now ... now they're not there anymore. So it's a strange feeling, a really strange feeling," he said. "I feel sorry for everybody in Germany. All the people there who have lost some family members."

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Dorothee Thiesing and Martin Meissner in Haltern, David Rising and Geir Moulson in Berlin, Jorge Sainz and Ciaran Giles in Madrid, Joseph Wilson in Barcelona, and Mike Corder in The Hague contributed to this report.