CARACAS, Venezuela (CNN) -- Three tear gas attacks were reported in Venezuela on Monday, one of them at the Vatican's diplomatic headquarters in Caracas.
One of the attacks, in which someone launched tear gas canisters at buildings or people, happened at the home of a private TV station's director. The third disrupted a press conference of a student leader who opposes efforts to make it possible for Venezuela's President Hugo Chavez to run for a third consecutive term.
No serious injuries were reported in any of the attacks, though a few people were overcome by the gas at the Vatican office.
A group calling itself Colectiva la Piedrita, which is said to support President Hugo Chavez's socialist agenda, claimed responsibility for the attack on the Vatican office, CNN affiliate Globovision TV said. Pamphlets left outside the building accused the Catholic Church of treason against the Venezuelan people.
Six tear gas canisters were fired in that incident, three of them landing deep inside the building, an attorney said at a news conference.
The Vatican nunciature in Caracas has been giving asylum since June to Nixon Moreno, a Venezuelan student leader accused of attempting to rape a policewoman and wounding several police officers in a 2006 shootout. Venezuela has not granted Moreno safe passage to leave the country.
Moreno's lawyer stood in front of the building Monday and angrily criticized the Venezuelan government after the tear gas attack. She said the canisters were manufactured by a company that supplies the Venezuelan military.
"We demand a response from the federal government," attorney Tamara Suju said in a news conference carried by Globovision. "We demand a response from the minister of justice."
A few hours later, a news conference at Central University of Venezuela by student leader Ricardo Sanchez came under attack, a TV report showed.
Sanchez, whose car was torched two days earlier, was denouncing violence as he stood, surrounded by reporters, on a plaza next to a street. A video on Globovision shows Sanchez and reporters ducking and looking toward where at least two canisters landed.
"These are the kinds of things that can't keep happening in Venezuela," Sanchez said afterward.
Sanchez blamed parapolice groups and complained that there have been no arrests or investigation.
Sanchez leads a student movement opposed to a proposed constitutional amendment that would allow Chavez to run for a third consecutive six-year term in 2012.
A referendum on the amendment will be held next month. Venezuelans narrowly rejected a similar measure in December 2007.
Chavez called for the referendum in late November, one week after Chavez-backed candidates won a majority of the seats in local elections that were seen as a test of his influence.
After Monday's tear gas attack at the university, Globovision showed two students holding empty canisters in front of a camera.
A group of students in the plaza chanted, "Who are we?" and answered, "Students."
"What do we want? ... Liberty."
Also attacked Monday was the home of Marcel Granier, the director of private station RCTV International. No one immediately claimed responsibility for that incident.
Monday's attack on the Vatican office, which happened before 6 a.m., was the sixth on the nunciature, Globovision said. The previous attack was with a fragmentation grenade, Suju said.
Colectiva la Piedrita previously claimed responsibility for similar attacks against Globovision, the homes of two journalists, the newspaper El Nuevo Pais and the headquarters for the Christian socialist party COPEI, Globovision said on its Web site.
Maria Carolina Gonzalez in Caracas contributed to this report for CNN.