The chief executive of Vivint Solar says he is “deeply disturbed” by allegations that several of his employees were involved in a pattern of racial harassment at a company warehouse in California.

In a lawsuit filed Monday in California Superior Court in Sacramento County, Teshawn Solomon, who is black, said white supervisors called him a racial epithet and compared him to a monkey. The lawsuit also claims that white employees used cardboard boxes to build a protective fort around their desks that was spray-painted with the words “white only.”

The structure remained in place for two weeks, the lawsuit claims.

“I want to firmly state that Vivint Solar has a zero-tolerance policy for racial discrimination and harassment in the workplace,” the company’s chief executive, David Bywater, said in a statement Thursday. “Our company is built on the strength of diversity.”

“The disturbing experience described by our former employee does not reflect the values or culture of Vivint Solar and stands in direct contradiction to our core values as a company,” the statement added.

Bywater said the company had completed an internal investigation that led to several employees being disciplined and another employee being fired. He said Vivint has hired an “independent third party” to review the company’s policies and procedures and recommend changes.

Bywater said Vivint also plans to implement company-wide harassment and discrimination training.

“That said, we strongly believe this was an isolated incident,” the statement said. “We also believe that some of the allegations in the lawsuit are inaccurate and are confident that the legal process will help bring clarity to the factual discrepancies between our internal findings and those described in the lawsuit.”

Solomon’s lawyer, Corey Bennett — an attorney with the employment law firm Matern Law Group — said Vivint’s statement makes it sound as if the company was unaware of racist behavior at the company until a lawsuit was filed. But, he said, a regional manager was shown a picture of the “white pride playhouse” months ago.

“We know the picture was submitted along with another employee’s unemployment benefits application in March,” he said. “We know that one of the culprits worked at multiple facilities over his tenure.”

“We know Mr. Solomon was targeted with the n-word throughout his employment,” he added. “And now the company says it has disciplined ‘several employees.’ Calling it an “isolated incident” might make themselves feel better, but it’s just not true.”

Vivint Solar has its headquarters in Lehi, Utah, and employs more than 4,000 people in 21 states.

In his suit, Solomon accuses his former employer of racial harassment and discrimination, both of which are violations of California’s Fair Employment and Housing Act. He also accuses Vivint Solar’s managers of failing to prevent racial discrimination and actively encouraging him not to take his complaints to the company’s human resources department.

Solomon said he knew he would have no opportunity to advance and make a better life for his family if he remained with Vivint Solar. After more than a year with the company, he resigned in March, deciding that he “could no longer tolerate the hostile work environment, brazenly racist conduct, and management’s indifference to it,” the suit states.

“Management did nothing after I complained,” Solomon said. “They didn’t hold anyone accountable. People continued joking about the fort for weeks because they knew management didn’t care about racism.”

Photos taken inside the warehouse and provided to The Washington Post by Bennett appear to show several desks surrounded by cardboard boxes, filing cabinets and stacks of water bottles. Scrawled above the “white only” sign are the words “Inspections Department.”

Bennett said the photos were taken by another employee who left the company after complaining about racial harassment and then passed the images to his client, who also took photos of the structure before it was taken down.

“If you look at that photo, you can get a sense they wanted to make their own little hideout,” Bennett said. “I think these people thought they could do whatever they wanted to without any oversight or accountability.”