SAN FRANCISCO — As people turned in droves to the video chatting app Zoom in recent weeks, the buzz caught Facebook’s attention. Inside the social network, that immediately set off a scramble.

Mark Zuckerberg, Facebook’s chief executive, ordered employees to ramp up and focus on the company’s own video chat projects, especially as use of its products also increased, said three people with knowledge of the plans, who declined to be identified because the details are confidential. On Facebook’s internal message boards, employees openly gawked at public data showing Zoom’s growing popularity, they said.

On Friday, Facebook unveiled one of its biggest expansions into videoconferencing with several new video chat features and services. They included video group chats for as many as 50 people on Facebook Messenger, WhatsApp video calls for up to eight people and video calls in Facebook Dating.

Mr. Zuckerberg is not the only tech titan with Zoom on his mind. Google this month made its video chat app, Meet, more accessible through Gmail. Cisco recently promoted its Webex teleconferencing service as highly secure compared with Zoom. And Verizon announced last week that it was acquiring BlueJeans Network, a videoconferencing service.

Tech and telecommunications giants are mobilizing against Zoom as the Silicon Valley company has become one of the biggest tech beneficiaries of the coronavirus outbreak. Over the past month, downloads of Zoom have increased 740 percent, according to App Annie, an analytics firm. Zoom has said it now has more than 300 million daily participants, up from 10 million before the pandemic.

Facebook, Google and others want a piece of that success. Behind the scenes, people with knowledge of the companies said, employees are sore that they have not grabbed more of the same buzz as Zoom, especially since many of the giants have offered their own video chat software — like Google Meet — for years.

In targeting Zoom, the tech behemoths are following a playbook of deploying their vast resources to outmuscle a smaller, fast-rising competitor. Last year, Facebook and Google trained their sights on TikTok, the Chinese-made video app, which had become a hit with young audiences. Often, the largest companies have opened up their wallets and snapped up tiny rivals to eliminate them as competition.

In an interview, Mr. Zuckerberg chafed at comparisons to Zoom and said video chat was just beginning to be a larger phenomenon as people aimed to digitally connect in more intimate ways.

“The world was already trending in this direction before Covid-19,” Mr. Zuckerberg said while using the new Facebook Messenger video product. “This is the trend in general — the ability to feel more present, even when you’re not physically together.”