The Los Angeles City Controller's office is investigating after NBCUniversal severely trimmed a row of trees outside its studios where members of SAG-AFTRA were picketing company executives, eliminating shade during a searing heatwave.

"Trees are essential to providing Angelenos with significant environmental and public health benefits, especially during a heatwave," LA City Controller Kenneth Mejia wrote on Twitter.

Last week, SAG-AFTRA's 160,000 actors and other media personalities joined the 11,000 Writers Guild of America (WGA) members who have been on the picket line since May as negotiations between the union and the Alliance of Motion Picture and Television Producers, which represents the studios, broke down. But excessive heat in parts of the country has led strike organizers to caution participants to stay hydrated and use sunscreen. Earlier this week, SAG-AFTRA cut short their Disney and Warner Bros. pickets, citing "extreme heat in LA."

On Monday, comedian Chris Stephens tweeted a picture of a row of trees, all with their limbs severely trimmed. "Quick shoutout to the good people at @UniversalPics for trimming the trees that gave our picket line shade right before a 90+ degree week," he wrote.

But NBCUniversal denied that this was malicious.

"We understand that the safety tree trimming of the Ficus trees we did on Barham Blvd. has created unintended challenges for demonstrators, that was not our intention," an NBCUniversal spokesperson said in a statement to CNN. NBCUniversal owns Universal Pictures. "In partnership with licensed arborists, we have pruned these trees annually at this time of year to ensure that the canopies are light ahead of the high wind season."

But Mejia said that the trees in question are managed by the city, not NBCUniversal, and added that trees should be trimmed every five years, not annually.

The Los Angeles Public Works Department also told CNN in a statement that the city didn't issue any tree trimming permits for the area outside Universal's offices.

The NBCUniversal spokesperson added that the company is working to offer additional accommodations such as pop-up tents and water. "We continue to openly communicate with the labor leaders on-site to work together during this time," they said.

A SAG-AFTRA spokesperson told CNN on Wednesday that the union and the WGA each filed unfair labor practices charges against NBCUniversal with the National Labor Relations Board. The two unions are working "to remedy this egregious violation of our members' rights," according to the spokesperson.

"SAG-AFTRA appreciates these efforts to ensure our members have a safe place to exercise their federal rights to join picket lines to demand a fair contract," they said. "Suspiciously timed construction that has forced picketers into streets without proper safety rails, and now tree trimming eliminating shade during a record heatwave, has forced SAG-AFTRA to determine that it cannot safely send its members to picket at NBCUniversal."

NBCUniversal did not immediately respond to a request for comment on the unfair labor practice charge.

Temperatures in Los Angeles this week are projected to hit around the low 90s, according to the National Weather Service. The agency says that exposure to direct sunlight can raise "feels like" temperatures by up to 15 degrees. Without shade, picketers likely would be in danger of heat stroke and heat exhaustion.

Exhaustion seems to be a key strategy in this fight.

Earlier this month, anonymous studio executives speaking to trade publication Deadline said that major studios are set on "[breaking] the WGA." They added that the plan "is to allow things to drag on until union members start losing their apartments and losing their houses."

In response, actor Ron Perlman took to Instagram Live saying, in part, "There's a lot of ways to lose your house. Some of it is financial, some of it is karma."

Perlman later clarified his comments in another post, saying "As you can imagine...somebody wishing that kind of harm on people in the same industry they call their own would engender a response," he said. "I don't wish anybody any harm."

He called on studio executives to "maintain a degree of humanity in all of this... There's got to be dignity if we are going to hold a mirror up and reflect the human experience, which is what we do as actors and as writers. And not just us. The drivers, the camera guys, the costume, the makeup people, the hair people, the electricians, the production designers. You want them to lose their f**king houses too? Is that what you're after? Just break everybody? How sad."

Perlman called the strike "a symptom of the soullessness of corporate America," adding that it's "about human dignity."

Labor disputes in the US have historically been lengthy and, at times, violent. From using union-busting Pinkerton detectives to infiltrate and physically assault striking workers to letting the federal government send troops to end strikes, employers have used a variety of tactics to brow-beat organizers and erode morale. But strikes have, in large part, paid off significantly for workers. For example, the 1960 WGA and SAG strikes resulted in increased residuals and the formation of pension and healthcare plans for members.