"Take them from the left," yelled the commander as he fired off a volley of shots at the enemy troops, ambushed as they peered through a window.
But as soon as he moves from his position, Mohammed is hit by three shots and falls.
The scene is not part of manoeuvres by the Iranian army - currently on high alert over the crisis with Iraq - but from the latest leisure activity and north American import to hit Tehran: paintball.
Two entrepreneurs say they have built the world's largest indoor paintball venue in a hangar at central Tehran's Enghelab (Revolution) sports complex, and have been flooded with calls from bored youth desperate for a go.
The fighting in the 2,600 square metre (28,000 square foot) hangar - which includes mock houses, sandbags and rope bridges - began on Sunday, with some 30 people decked out in combat fatigues dividing into two teams to do battle.
"It's great. It's got nothing to do with war. We unwind and above all learn teamwork," enthused Ahmad, a 21-year-old student.
"My captain ordered me to advance on an enemy position. I knew I would be injured, but orders are orders and I had to follow them," he added.
The game has been introduced to Iran by Hamid Nikpour and Siamak Salehpour, two computer engineers aged 41 and 30 respectively, who had decided to move back home from Montreal, Canada, three years ago.
They said the equipment and the venue cost some four billion rials (about 500,000 dollars), and should quickly pay off.
"It's not a war game," insisted Salehpour. "Iranian youth have too little in the way of leisure, so they can come and unwind here."
He also said state education officials had also expressed interest in sending pupils to the game for their defence classes - which usually involve real guns.
Nikpour said that in a period of international tension focusing on Iran's neighbour Iraq he had problems importing the imitation guns and other equipment from Canada.
"But we obtained the approval of the defence ministry, which checked the weapons. They are in aluminium and can't be converted into real guns," he said.
"There is no restriction on women, but we preferred to restrict it to men to begin with," he added.
Even if the facility is opened to women later, the law bars mixed sessions, so Iranian women will have to go without the enjoyment of shooting men for the time being.
But a national federation has already been formed and dozens of people have signed up for the opening combats, with the prospect of taking part eventually in international contests.
"Up to now there has been no advertising, but every day we get 30 to 40 calls. Seven teams of 10 people have already been formed," Nikpour said.
In a country where 70 percent of the population is aged under 30, "paintball is perfect for expending energy," said Nikpour, an air force veteran of the bloody 1980-1988 Iran-Iraq war.
"Since the war, Iranian society is evolving fast. We see it every day."
However, players will need cash as well as energy - fees range from eight to 12 dollars each, a lot for the average Iranian.
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