A few hundred men and women, some carrying weapons and in uniform, gathered late Saturday in their camp outside the state security agency building in the center of town.

Now called the Army of the Southeast, the pro-Russian separatists seized the building almost a month ago. The time had come, their leaders said, to make a decision about fighting a real war against Ukraine.

Men and women scurried out of their tents to hear what the leaders were saying. One middle-aged woman rushed to join the crowd with a big wooden club in her hands.

A stout man in camouflage who referred to himself as “a commander of a combat battalion” stepped in front of barricade with a microphone in his hand. He called for mobilization “in revenge for what happened in Odessa.” A day earlier, more than 40 people died in street fighting and a fire in the port city, and the separatists in Luhansk were angry.

Earlier Saturday, the “People’s Governor of Luhansk,” Valery Bolotov, imposed a curfew on the city of 455,000 near the Russian border from 11 p.m. to 6 a.m. His audio-recorded ultimatum to Ukrainian officials blared from speakers in the camp all day, every few minutes it seemed. Bolotov set a deadline for local law enforcement commanders and military bases to swear their allegiance to the Army of the Southeast; otherwise, they would be considered “traitors” and “enemies of the people.”

Map: Russia and Ukraine are positioning their troops for war.

At one point, a black Mazda with a Ukrainian flag flying outside a window drove past the camp’s entrance. A guard fired a pistol into the air, and someone in the camp threw a stone at the car.

The ultimatum’s deadline passed, but it was unclear whether any commanders of Ukrainian military units had sworn allegiance to the Army of the Southeast. So the camp commanders ordered the activists to break into 20-man units, choose their leaders, and line up on the plaza in front of the building. Many of the men quickly obeyed, forming tight rows, while the women looked on.

“Enough staring,” the commander said in a voice that left no room for doubt. “We have serious actions ahead of us tonight. It is now or never. We invite only the devoted ones to join us for the war against Kiev — everybody who is not ready, goodbye.”

Half an hour later, the action started. Gunfire and grenade explosions were heard outside a military draft office, a military site but a lightly guarded one. At least three people were wounded during the battle.

Bolotov’s spokesman, Vasily Nikitin, said the Ukrainians started the fight by “shooting at unarmed people, and our fighters arrived to help out.” That could not be confirmed, but by 10 p.m., the militia had seized the center.

But most residents of Luhansk continued to live peaceful lives. Families took children to the amusement park by the TV tower. A wedding procession drove past the pro-Russian demonstration outside the seized regional council, cars honking.

At a little jewelry store, a customer looked at gold chains and discussed prices with the owner. The curfew declared in their city was not good news for business, they said.

Meanwhile, in a heavy rain, the camp’s activists reinforced their barricades, bringing in more sand and tires and filling bottles with gas for their supply of molotov cocktails. Women in the field kitchen said they prepare more than 3,000 sandwiches for “the boys at barricades” every night and constantly cook huge cauldrons of soup.

Their commander’s voice over loudspeakers repeated: “Our first target is Kiev. Our first target is Kiev.”

“We are prepared for the war morally, but we don’t have enough surgeons if something as awful as in Odessa happens,” said Margarita Chebatareva, a nurse at the camp’s hospital, adding that she would treat the wounded no matter which side they were from.