Hundreds of Venezuelan police and troops broke up four makeshift camps maintained by student protesters, arresting 243 people Thursday in pre-dawn raids. Officials reported that one officer was killed and another injured after the raids.

The tent cities were erected more than a month ago in front of the offices of the United Nations and in better-off neighborhoods in the capital to protest against President Nicolas Maduro's socialist government.

Speaking at a news conference outside the detention center where the protesters were being held, Interior Minister Miguel Rodriguez Torres presented homemade mortars, guns and Molotov cocktails that he said were seized at the camps and used to carry out "terrorist" acts against security forces.

"This shows there was an entire logistical apparatus in place," Rodriguez Torres said, seeking to counter claims that the anti-government movement has been peaceful and spontaneous.

Torres said an "impressive" amount of drugs were also found. He performed a test in front of journalists to determine the purity of cocaine that he said was confiscated at the camps.

One officer was killed and another wounded by gunfire. Maduro, who was at an event in Caracas to deliver homes to low-income families, said the officer was killed by a sniper in violence that erupted as police cleared the streets of debris in the leafy Chacao district where the U.N. office is located.

The dismantling of the camps was announced just hours before a top opposition leader, Leopoldo Lopez, was scheduled to appear in court after being in custody since February. The hearing on whether he should begin trial on charges of inciting violence at anti-government protests was suspended and he was taken back to a military prison almost as soon as he arrived at the courthouse downtown.

Witnesses near the U.N. office said hundreds of National Guardsmen began arriving after 3 a.m. on Thursday morning and were greeted angrily by neighbors who launched objects and insults from nearby balconies.

Torres said security forces relied on surprise rather than aggressive force to round up the protesters. He said the detainees would be charged, but it wasn't clear when that would happen.

Hours later, shoes, clothes and destroyed banners littered the streets where the makeshift campground once stood. A few dozen neighbors built barricades to block traffic, demanding the release of the students.

"How can this be allowed when the constitution guarantees the right to peaceful protest," said Anais Serrano, a real estate agent. "These kids weren't anything bad."

The raids came as the U.S. Congress began debate Thursday on economic sanctions against top Venezuelan officials.

The Obama administration argued at a Senate committee hearing that sanctions would be premature while dialogue continues between Maduro's government and some members of the opposition.

Roberta Jacobson, U.S. assistant secretary of state for Western Hemisphere affairs, said some opposition leaders have urged the United States not to go forward with sanctions.

"They have asked us not to pursue them at this time," Jacobson said.

The legislation in both chambers is relatively modest. It centers on freezing assets and banning visas for Venezuelan officials who crushed anti-government protests. It would also boost aid for pro-democracy and civil society groups.

U.S. Sen. Bob Menendez, the Senate Foreign Relations Committee chairman who introduced the legislation, said he would like to hear directly from leaders who oppose the sanctions.

Anti-Maduro groups are divided on how much to engage with the government. Students and hardliners are boycotting the talks, which they consider a ploy by Maduro to deflect foreign criticism of his handling of the crisis.

The South American country has been roiled since February by demonstrations that have resulted in 42 deaths on all sides and left 785 injured. At least 2,200 people have been arrested in connection with the protests over the last few months.

Maduro's administration has grown increasingly fed up with the demonstrations and last week announced it had arrested 58 foreigners, including an American, on suspicion of inciting violent street protests against the government.

Opponents have repeatedly rejected Maduro's frequent allegations that the protests are seeking his overthrow, saying he is trying to distract attention from grueling economic crisis marked by 57 percent inflation and record shortages of basic goods.

U.S. Sen. Marco Rubio, a sponsor of the sanctions legislation in the Senate, said the message that penalties would carry is important. The move comes as human rights groups accuse Venezuelan security officials of arresting, torturing and even killing unarmed demonstrators.

"This is happening in our very own hemisphere," Rubio said in a telephone interview with The Associated Press. He said sanctions should target anyone responsible for human rights violations, refusing to rule out Maduro as a potential target.

Action now would show the U.S. is "firmly on the side of the democratic aspirations of the Venezuelan people," Rubio said.