Buenos Aires (CNN) -- Police defused a bomb at a Buenos Aires theater Tuesday, a day before a former Colombian president was scheduled to speak there.
Authorities offered different assessments of the danger the explosive posed, and when it was set to go off.
A judge who investigated the Gran Rex theater said the bomb was set to be detonated around 4:30 p.m. Wednesday afternoon, when former Colombian President Alvaro Uribe is scheduled to speak.
"It was a simple apparatus, but one that could have caused the death of people closest to it," Judge Norberto Oyarbide told reporters.
Later Tuesday, federal police said the bomb was designed more to cause commotion than serious damage, and had been set to go off on Tuesday afternoon, according to the state-run Telam news agency.
"It was designed to produce shocking sounds," police spokesman Commissioner Nestor Rodriguez said.
A theater employee alerted authorities after finding the device, Oyarbide said.
"Undoubtedly it looked like a bomb. You could see two pieces, and a cell phone, and it was connected in the middle," said Hector Fernandez, a theater employee.
Authorities were investigating to determine who placed it in the theater.
Colombia's defense minister condemned the apparent attack attempt and called for an investigation.
Last week, a former top official from Uribe's administration survived an assassination attempt -- a daylight bombing in Colombia's capital.
Uribe was Colombia's president from 2002-2010, and was known for his focus on improving security and his tough stance on leftist guerrillas.
Uribe is scheduled to speak on at an international entrepreneurs conference Wednesday at the Gran Rex, one of the largest theaters in Buenos Aires.
A description of the event on the WOM Leadership Symposium's website said Uribe would be discussing his role in "the transformation of Colombia."
"In 2002, he found a country beset by guerrillas and overcome by uncertainty and despair. Eight years later, he handed over a country that was safe, thriving and respected by the international community as one of the most attractive countries for foreign investment," the website says.
A statement on the website said the conference would continue as scheduled Wednesday.
Human rights groups are planning a demonstration Wednesday afternoon near the theater to protest the former Colombian president's participation in the symposium.
An announcement of the protest describes Uribe as a "true threat to the region," arguing that "in the name of the fight against 'terrorism' he committed the most atrocious crimes against the Colombian people."
CNN's Jose Manuel Rodriguez and journalist Fernando Ramos contributed to this report.