University students blocked one lane of a major highway hours after Radio Caracas Television ceased broadcasting at midnight and was replaced with a new state-funded channel. Chavez had refused to renew RCTV's broadcast license, accusing it of "subversive" activities and of backing a 2002 coup against him.
Two students were injured by rubber bullets and a third was hit with a tear gas canister, said Ana Teresa Yepez, an administrator at Caracas' Metropolitan University. She said about 20 protesters were treated for inhaling tear gas.
The new public channel, TVES, launched its transmissions with artists singing pro-Chavez music, then carried an exercise program and a talk show, interspersed with government ads proclaiming, "Now Venezuela belongs to everyone."
Crowds of students demonstrated across Caracas, saying they fear for the future of free speech.
"I plan to keep protesting because we're Venezuelans and it's our right," said Valentina Ramos, 17, a Metropolitan University student who was hit in the head with a tear gas canister and received stitches.
She said the protest was peaceful, but National Guard troops said they acted after students hurled rocks and sticks. Police said 11 officers were injured in separate protests on Sunday that were broken up with water cannon and tear gas.
In the countdown to the midnight deadline, thousands of RCTV backers banged pots in protest and played recordings of sirens. Some fired gunshots into the air.
At the same time, thousands of government supporters reveled in the streets as they watched the changeover on large TV screens, seeing RCTV's signal go black and then be replaced by a TVES logo featuring Venezuela's national colors.
Others launched fireworks and danced to the classic salsa tune "Todo tiene su final" — "Everything Has Its End."
Earlier Sunday, police broke up an opposition protest using a water cannon and tear gas and later clashed with protesters who set afire trash heaps in affluent eastern Caracas. Police said some protesters fired shots, and others threw rocks and bottles. Police said 11 officers were injured.
Inside the studios of RCTV — the sole opposition-aligned TV station with nationwide reach — disheartened actors and comedians wept and embraced in the final minutes on the air.
They bowed their heads in prayer, and presenter Nelson Bustamante declared: "Long live Venezuela! We will return soon."
Chavez says he is democratizing the airwaves by turning the network's signal over to public use. His opponents condemned the move as an assault on free speech.
Germany, which holds the European Union presidency, expressed concern that Venezuela let RCTV's license expire "without holding an open competition for the successor license." It said the EU expects that Venezuela will uphold freedom of speech and "support pluralism."
Founded in 1953, RCTV had broadcast talk shows, sports, soap operas and a popular comedy program that poked fun at presidents — including Chavez — for decades. It had some 3,000 employees, including 200 journalists.
RCTV was regularly the top channel in viewer ratings, but Chavez accused the network of "poisoning" Venezuelans with programming that promotes capitalism, violating broadcast laws and other infractions.
The government promises TVES will be more diverse, buying 70 percent of its content from independent Venezuelan producers. It will carry sports, news and an educational program for children emphasizing socialist values, as well as foreign-made programs such as National Geographic documentaries.
"We've come here to start a new television with the true face of the people, the face that was hidden, the face that they didn't allow us to show," said Roman Chalbaud, a pro-Chavez filmmaker appointed by the government to TVES' board of directors.
Chavez, who says he is steering Venezuela toward socialism, accuses RCTV of supporting a short-lived 2002 coup. RCTV's journalists argue violent demonstrations staged by Chavez's supporters outside the station's studios prevented them from covering the news at the time.
RCTV's shutdown leaves 24-hour Globovision news channel as the only other major opposition-sided station, and it is not seen in all parts of the country. Other channels once critical of Chavez have toned down their coverage.
Chavez's decision "marks a turn toward totalitarianism," said RCTV's top executive, Marcel Granier, while hundreds of protesters chanted "No to the shutdown!" outside the station. "He's losing international recognition and he's losing the respect of his people."