It was half past five in the morning on Saturday, when Krzysztof M. Kozak ’10 was woken up by a call from his mother in Warsaw.

The Polish president had been killed in a plane crash, his mother told him, asking him to check the news.

For many Polish undergraduates like Kozak, the deaths of Polish President Lech Kaczynski and top political and military leaders in a plane crash in western Russia over the weekend came as a shock.

“Imagine, you know, having [President] Obama, Michelle Obama,...and the governor of the central bank...die at the same moment,” said Dominik Nieszporowski ’12. “It was an incredible tragedy.”

The deaths are even more shocking in light of the historical context, Nieszporowski added. In 1940, Stalin ordered a massacre of more than 20,000 Polish officials and intellectuals in Russia. Seventy years later, President Kacynski and 96 others—including many top Polish officials—died in the same location while en route to commemorate the massacre’s 70th anniversary.

The crash has led to unprecedented unity among Polish students on campus, said Jakub Dolecki ’11. Members of the Harvard Polish Society planned commemoration events over the weekend, and many Polish students at Harvard had planned to attend a Catholic Mass at a Polish church in southern Boston last night, Dolecki said.

The Polish Society will also hold a meeting this Friday, which will coincide with the end of official national mourning in Poland.

Other Polish students in the area expressed grief through activism. Two MIT freshmen organized a screening of a film detailing the 1940 massacre for students at MIT and Harvard on Saturday night. The same night, Kozak said he and his friends put up a small Polish flag on the wall of University Hall, but it was taken down the following morning.

He added that the Polish Society is currently negotiating with the Office of the University Marshal to hang a Polish flag with a black ribbon on the flag pole adjacent to the John Harvard statue.

Kozak said that he also planned to light candles in front of the plaques of two Polish heroes in Cambridge Common.

Despite their grief, most Polish students showed optimism about both Poland’s domestic stability and the country’s ability to recover from the tragedy.

“Poland has encountered many challenges in the past few centuries,” Dolecki said, “and we always recovered.”

Although many top leaders were killed, Nieszporowski said he believedsthe national tragedy will not spawn a political or economic crisis.

According to Kozak, it is “amazing” that Russian leaders have shown a “fast” and “caring” response, which has challenged pessimism about the fragile relationship between Poland and Russia, he added.