Hungarian border guards on Tuesday fired warning shots to deter dozens of people from crossing from the Serbian side following a reported spike in attempts to get into the EU's passport-free zone.
Police presented camera footage dated 05:30 am local time (0430 GMT) showing people, many wearing backpacks, jumping over a wall and running past an iron gate at the Roszke border-crossing point.
"A group of some 60-70 illegal migrants tried to enter Hungarian territory from Serbia in an organised and aggressive way," Karoly Papp, a senior police official, told reporters in Budapest.
"One of the three armed security guards on duty fired three warning shots into the air, after which most of the group ran back into Serbia, while police reinforcements arrived," he added.
Four men who ran some 60 to 70 metres into Hungary were later caught and arrested, he said, adding that police had "hermetically sealed off" the area around Roszke.
A police spokesman for the area Gergely Varkonyi told AFP that "some" of the group were still at large.
Meanwhile in neighbouring Serbia border police "found 37 migrants who tried illegally to cross into Hungary early in the morning around 5:00 am".
The group had tried to cross by cutting the fence on the Hungarian side near the Horgos 2 border crossing, Serbia's interior ministry said in a statement. They were later handed over to a police station in the nearby town of Kanjiza.
Gyorgy Bakondi, an adviser to nationalist Prime Minister Viktor Orban, cited police statistics which he said showed a sharp rise in attempts to cross Hungary's southern borders.
There had been 3,400 attempts made so far this month, compared to just several hundred a month last year, he said.
Earlier this month, Hungarian police said it had sent reinforcements to the border and launched a boat patrol on the river Tisza, which forms part of its frontier with Serbia.
In 2015, at the peak of the migration surge in Europe, would-be migrants and asylum seekers clashed with Hungarian riot police at Roszke, a day after the border was sealed with a razorwire-topped fence.
The hardline anti-immigration Orban says he is defending a border of the EU's passport-free Schengen zone. But he has been criticised by Brussels and rights groups for his tough border security policy.
In 2015 after the border was sealed with a razorwire-topped fence at Roszke, would-be migrants and asylum seekers clashed with Hungarian riot police