SAN CRISTOBAL, Venezuela (AP) — The battle for Venezuela is being fought as vigorously online as in the streets, with Internet service cut off to a strife-torn university city and the government blocking selected websites and a “walkie-talkie” service widely used by protesters.

Internet connectivity was gradually restored to San Cristobal, capital of the western border state of Tachira, Friday morning after an outage of more than 30 hours that also affected smartphones.

The tense streets smelled like burned trash after another night in which police firing tear gas broke up protests as they had Wednesday night when Internet service was cut.

Public transit was not operating, many street lights were dark and low-flying air force jets buzzed the city.

“It’s an abuse!” Jeffrey Guerrero, a flour wholesaler, complained before Internet service was restored. “We’ve had to find out what’s happening in our city from others.” He held up his iPhone to show how his Twitter service had halted.

The socialist government later blamed “accidents” and “vandalism” by right-wing groups for the outage.

The current wave of anti-government demonstrations, the fiercest unrest since President Hugo Chavez died last March, began in early February in San Cristobal, home to one private and three public universities.

On Thursday night, the U.S. company Zello told The Associated Press that Venezuela’s state-run telecoms company, CANTV, had blocked access to the push-to-talk “walkie-talkie” app for smartphones and computers that has been a hugely popular organizing tool for protesters from Egypt to Ukraine.

Zello supports up to 600 users on a single channel, and company CEO Bill Moore said it became the No. 1 app in Ukraine on Thursday for both the iOS and Android operating systems. In just one day this week, Zello reported more than 150,000 downloads in Venezuela.

Venezuela’s information war escalated last week as the government blocked images on Twitter after violence in Caracas claimed three lives amid protests over woes including rampant inflation, food shortages and one of the world’s highest murder rates.

The socialist government cemented its near-monopoly on broadcast media during Chavez’s 14-year rule, and social media have been crucial for young opposition activists as they organize and exchange information on deaths, injuries and arrests.

Activists also reported a serious nationwide degradation in Internet service provided by CANTV, which handles about 90 percent of the country’s traffic.

Websites blocked included NTN24.com, run by the eponymous Colombia-based regional news network, and online pastebin.com bulletin boards that cyberactivists use to anonymously share information.

President Nicolas Maduro ordered NTN24 removed from the air last week after it broadcast video of a student killed by a gunshot to the head in Caracas.

U.S.-based company Renesys, a top analyzer of global Internet traffic, confirmed the website blocking and service degradation, but said it could not determine if CANTV was decreasing bandwidth.

“I certainly don’t know from our data if it is deliberate, although given the context, it seems plausible,” said Renesys researcher Doug Madory.

Venezuela’s traffic to its close ally Cuba over the ALBA-1 undersea cable, meanwhile, appeared unaffected, he said.

Programmer and cyberactivist Jose Luis Rivas said the Internet went out in most of the city of 600,000 about midnight Wednesday.

Since protests accelerated last week, activists have posted YouTube videos of riot police and National Guard breaking up demonstrations and, they claim, firing at unarmed civilians. Sometimes, the security forces are accompanied by pistol-packing motorcycle gangs of Chavista loyalists.

Rivas said that on Wednesday night, before the Internet went out in San Cristobal, people were live-streaming video of a crackdown by security forces.

Cutting off Internet deprived people of their only access to uncensored information and Rivas said people told him “they felt fear because they were no longer informed.”

On Friday, the state news agency AVN quoted Science and Technology Minister Manuel Fernandez as blaming the Internet outage in Tachira on “severing of fiber optic lines by accident in some cases and in others from vandalism.”

Hacktivists also have been attacking government websites and Fernandez said Friday in a TV interview that 147 had been defaced or rendered unreachable with denial-of-service attacks, or data-packet floods, over the previous 11 days.

He said many had been restored, but the state television network’s site, vtv.gob.ve, remained offline Friday night.

Images, meanwhile, were visible again on Twitter after last week’s outage.

Company spokesman Nu Wexler said Thursday that measures which he did not specify were taken to “ensure continuity of service.”

Twitter also continued to tweet a workaround that lets users in Venezuela receive tweets on their cellphones via text message.

Government officials have accused “putschists” of spreading disinformation via social networks as part of what they claimed is a coordinated campaign to overthrow the government.

Even before the protests, which have claimed at least six lives since Feb. 12, Venezuela had been blocking websites that track the black market rate for the country’s currency. For several weeks, that knocked out access to the popular Web address-shortening application Bitly.

Venezuelans who want to reach such sites are increasingly using proxy services, which have long been employed by people in China and Iran to circumvent government censors.

The international director of the Electronic Frontier Foundation, Danny O’Brien, said he thought Venezuelan net censorship has been “somewhat haphazard and arbitrary.”

Nearly half Venezuela’s population relies on government-controlled media as their sole information source, the rest on the Internet.

But cutting off Internet is not smart political strategy, said O’Brien.

“I think the important lesson people should learn from these Internet blackouts is that they just throw fuel on the flames of civil unrest.”