Police in Puerto Cabello say some of the suspects are under the age of 18.
Spear, 29, and Thomas Henry Berry, 39, were killed Monday night after resisting a robbery. Their car had broken down on a roadside near Puerto Cabello when they were killed.
Investigators say robbers shot and killed the two and also injured their 5-year-old daughter, Maya, when the family tried to foil the attack by locking themselves inside their car.
Family members say they learned of the tragedy as most everyone else did - on the news.
"This is the deepest moment that we ever had in our core family and truly, there's no words to describe our pain. This is something that should have never happened," said Spear's father, Rafael Spear.
Maya was reported to be in stable condition after being treated for a leg wound, according to authorities. Officials say she is staying with relatives in Caracas.
In response to the killings, President Nicolas Maduro announced that he would convene a security meeting on Wednesday that had originally been scheduled for the end of January. It is to bring together state governors and mayors of Venezuela's 79 most dangerous cities.
Fatal shootings are common in armed robberies in Venezuela, and rampant kidnappings have ensnared even foreign ambassadors and professional baseball players.
Violent crime soared during the 14-year rule of Hugo Chavez, who died of cancer last March. The country has one of the world's highest murder rates - the United Nations has ranked it fifth globally.
The couple's slaying followed a pattern of late-night assaults carried out by disabling cars with obstacles placed on roadways. Investigators say their four-door sedan hit "a sharp object that had been placed on the highway" which punctured at least two of its tires.
After their car was damaged, officials said two tow trucks arrived almost immediately, and the attack occurred after the car had been lifted onto one of the trucks. When the family locked themselves in the car, police said the assailants fired at least six shots.
It could not immediately be determined if Spear and Berry had called the tow trucks, or if any of the drivers were among those arrested for suspected involvement in the killings.
The couple's friends say the two were divorced but had a good relationship. The two had spent New Year's in the mountains of western Venezuela with their daughter, then visited the plains of Apure state. They were on their way back to Caracas at the time of the attack.
Spear was crowned Miss Venezuela in 2004, was fifth runner-up in the Miss Universe pageant the following year and had acted in numerous soap operas, most recently in "Pasion Prohibida," for the U.S.-based Telemundo network.
The Associated Press contributed to this report.