"I announce to the country that capture seven suspects was achieved in the unfortunate murder of Monica Spear," Interior Minister Miguel Rodriguez Torres said in a statement.
"Among those arrested were the perpetrators of the double homicide," he said.
Spear, 29, and ex-husband Thomas Henry Berry, a 39-year-old Briton, were shot and killed at close range in their car Monday night on an isolated stretch of highway in western Venezuela.
Their 5-year-old daughter, Maya, was also in the car and was shot as she witnessed her parents' murder.
She is in stable condition with relatives in Caracas after treatment for a leg wound, authorities said.
The two teenage suspects in the killing are age 15 and 17, authorities said. The adult suspects range from 19 to 39, they said.
Several belongings of the victims were seized in the arrest, officials cited by Venezuelan newspaper El Universal said.
The accused bandits fired at least six shots into the vehicle.
The killings at about 10:30 p.m. followed a pattern of late-night assaults carried out by gangs of criminals who disable cars with obstacles placed on roadways, Fox News Latino reported.
The couple were driving on an isolated, badly maintained stretch of road when their four-door sedan hit "a sharp object" on the highway that punctured at least two of its tires, chief national police investigator Jose Gregorio Sierralta told reporters.
Two tow trucks arrived almost immediately, and the attack occurred after the car was lifted onto one of the trucks, Sierralta said.
Spear and Berry locked themselves in the car when they saw the assailants coming, he said, and the assailants fired at least six shots.
Spear, a naturalized U.S. citizen, split her time between Caracas and Miami.
Her family in Florida had told her not to spend much time in Venezuela because of safety concerns.
"There's no words to describe our pain. This is something that should have never happened," Spear's father, Rafael Spear, told News 13 cable channel in Orlando, Fla.
"Our plan is to bring Maya since she's now alone in this world," Spear said. "Our plan is to bring her here and have her grow up in the states, if the U.S. government allows us to do that."