CNN  — 

The US military has issued an apology after soldiers accidentally stormed a factory in Bulgaria that produces processing machinery for olive oil during a training exercise last month.

US soldiers of the 173rd Airborne Brigade had been practicing for days how to seize and secure the Cheshnegirovo decommissioned airfield in Bulgaria, training that included clearing bunkers across the airfield, according to a statement from the US Army Europe and Africa released Tuesday. During an exercise on May 11, the soldiers cleared a building next to the airfield that “they believed was part of the training area, but that was occupied by Bulgarian civilians operating a private business.” No weapons were fired, the US military also said.

“The U.S. Army takes training seriously and prioritizes the safety of our soldiers, our allies, and civilians. We sincerely apologize to the business and its employees,” the US military said in the statement. “We always learn from these exercises and are fully investigating the cause of this mistake. We will implement rigorous procedures to clearly define our training areas and prevent this type of incident in the future.”

Video from the factory’s security cameras obtained by CNN affiliate Nova TV appears to show US troops in military gear holding guns and walking in and out of the factory as others look on.

Video from the factory's security cameras obtained by CNN affiliate Nova TV appears to show US troops in military gear holding guns and walking in and out of the factory as others look on.

Marin Dimitrov, 63, the owner of Kim Engineering, the factory stormed by US troops, and his son, Bozhidar Dimitrov, 33, told CNN Wednesday that military exercises have been conducted routinely in the nearby airfield, but for the 12 years the factory has been there, there haven’t been any incidents. Bozhidar said no one contacted them and told them the military would be training on their property that day.

“We don’t have anything against the activities, about training, but the problem was that no one asked us if it was OK to enter. … We just needed to know that it was going to happen so that we can warn our workers and to avoid this threat to them,” Bozhidar Dimitrov said.

“That day around 1:30 p.m., through the fence, which is a robust brick fence, American soldiers jumped over, seven in number, and came out in the zone of our factory. … With pointed guns they went inside the rooms,” Marin Dimitrov said. “First they saw two people and told them, ‘Sit down, sit down.’ And the people, what can they do? They got scared and sat down where they could, while (the soldiers) continued on with their assignment,” Marin Dimitrov said.

“The US soldiers went through the whole premises of the factory. We are just a few people, seven employees, and so everyone saw them, and everyone reacted based on what his personality is, so to say, some got more scared, others less, that’s normal,” Marin Dimitrov said.

“Then they just left from the same place from where they entered [over the fence], they just left the premises [of the factory] and that was it,” said Marin Dimitrov.

The whole ordeal lasted about 22 to 30 minutes total, Bozhidar Dimitrov said.

Bozhidar Dimitrov told CNN he arrived at the factory as soldiers were leaving the building and were heading toward the fence. He said he entered the building as he was worried about the employees. They told him what happened and that they believe those were US soldiers as they were speaking in English. Bozhidar Dimitrov then went to the office building and checked the security cameras.

Bozhidar Dimitrov said neither his father Marin nor another associate were present at the factory when the incident happened and that the seven workers in the factory that day “got scared” by the incident.

Over the next day he spoke with a lawyer, took the security camera video and filed a formal complaint.

Asked how he felt about what had happened, Bozhidar Dimitrov said, “It was kind of like in a movie, something that I had seen in the movies and didn’t expect to happen in real life.”

“I was really shocked to see that, but my main concern was to see if any one of the workers was OK. So I tried to calm, because you know not to freak out,” he said.

When asked what action they would like to see taken, Marin Dimitrov said, “for this not to happen again, why – because we here, our unit, our factory is sharing the same fence with the airport. There will be a training again, we know that, (…) we just want attention to be paid so that this thing won’t be happening.”

Marin Dimitrov said, at the moment, they haven’t started a legal case, “because we have submitted a complaint in the prosecutor’s office and the prosecutor’s office has to make a statement and a decision.”

“After that we could potentially start a case,” Marin Dimitrov said.

Asked if they have received an apology from the US or the Bulgarian government, Bozhidar Dimitrov said his father has spoken with a US military representative and “he got an apology from them.” He also spoke with representatives from the Bulgarian military.

CNN has reached out to the US embassy in Bulgaria, Bulgaria’s Interior Ministry and Defense Ministry for comment.

Bulgarian President Rumen Radev condemned the incident and said he expects there will be an investigation, CNN affiliate Nova TV reported Monday.

“It is inadmissible to have the lives of Bulgarian citizens disturbed and put at risk by military formations, whether Bulgarian or belonging to a foreign army,” Radev said. “The exercises with our allies on the territory of Bulgaria should contribute to building security and trust in collective defense, not breed tension.”

CNN’s Ellie Kaufman, Sarah Dean and Duarte Mendonça contributed to this report.