The Marauders graduated in 1978 and J+L died in 1981. That means that while the Marauders were in 7th year, students in years 1, 2, 3 & 4 would be in years 4, 5, 6 & 7 in 1981, if that makes any sense???
So, I’d imagine Hogwarts would hear the news the next morning from the Daily Prophet, or maybe Dumbledore announced it at the Halloween Feast or something… but either way, the younger students would be cheering and celebrating at finding out that You-Know-Who had been defeated.
On the other hand, the older students, who had been in school at the same time as the Marauders, would be truly devastated.
James and Lily Potter dead? The former Head Boy & Girl of Gryffindor House? Gryffindor quidditch team captain, James? Tutor for students of all houses, Lily? Legendary troublemaker/prankster, James? Muggleborn rights activist, Lily?
Although Peter faked his death, nobody knew it was fake… And say all you want about Peter, but he had to have been a cool guy if he was a part of the Marauders. So of course, people were heartbroken about him too.
Peter Pettigrew dead? The boy who kindly shared food stolen from the kitchens with students who skipped meals to study, Peter? Legendary Marauder, Peter?
It hurts me to even imagine what went through people’s minds when they found out Sirius allegedly led James and Lily to their deaths.
Sirius Black, the cause of his best friend’s murder? Prankster extraordinaire, Sirius? Loyal to all of his close friends, Sirius? Protective over students who were bullied and/or had broken homes, Sirius?
The students were probably just as shocked as the professors were. Even though it was a day for celebration, students and professors, who truly knew the Marauders, felt deceived and lied to because after everything each Marauder had been through, none of them had deserved this fate.