Members of Brazilian federal police bomb squad pack their gear after detonating a suspicious package near the men's cycling road race final. (Victor R. Caivano/AP)

Authorities blew up a suspicious bag near the finish line of the men's cycling road race. A stray bullet fell through the top of the media tent at the Olympic equestrian center. Day 1 of the Summer Games was full of close calls and false alarms.

In the end, neither incident amounted to much — no one was hurt and terrorism was not suspected in either case — but they were indicative of underlying tensions here, where anything suspicious can seem like a serious threat in these heavily patrolled Games.

The scare in Copacabana started Saturday morning, when a resident of one of the apartment buildings overlooking the course on Avenida Atlânica, the main street that runs alongside Copacabana Beach, saw an unattended rucksack on the top of a container and alerted police. The container was full of electrical equipment and stored behind fences.

The Federal Police’s bomb squad was called and detonated the bag with a small, controlled explosion, said Sergeant Magno Santos, a member of Brazil’s National Force — an equivalent of the U.S. National Guard — which is providing extra security during the Games.

Andrada said authorities had determined the suspicious package was only a misplaced backpack and posed no danger.

“The controlled explosion we had was more a result of us being overcautious than anything else,” Rio 2016 Communications Director Mario Andrada said. “It causes anxiety, I know. But we have to react to a global worry. We’re not living in an easy moment. The authorities opted for the safe side.”

The area was isolated and sealed off from around 11.30 a.m. until 1:30 p.m. local time, said Julio da Silva, 50, an electrician who was working in the area. The explosion left a small hole in the container.

“They asked us to clear the area and isolated the whole area,” da Silvasaid.

Cleiton Lima, 38, a waiter at the Garota de Copacabana restaurant, which faces the container said ecurity forces cleared the restaurant’s terrace for the controlled explosion. Some customers left; others sheltered inside the restaurant.

“People were calm,” Lima said.

Brazilian authorities have deployed some 88,000 security forces to guard the Games, and their presence can be seen and felt on the streets and particularly at venues.

At the equestrian media center, a bullet punctured the roof at around 1:45 p.m. local time, leaving a hole just to the left of a stage constructed for media conferences. It landed about 10 feet from Jon Stroud, a British freelance equestrian photographer.

“I heard a massive bang just behind me,” Stroud said. “I just assumed it was a light that had come down or somebody dropped a camera, the usual things that happen in press centers. And then we looked, and just were absolutely gobsmacked to find that there was a bullet sitting on the ground just behind us.”

Investigators determined the media center was not a target and the “stray bullet” has “nothing to do with the Games,” Andrada said. But Andrada said authorities did not know, or at least did not share with him, from where the bullet had come, which raised the question of how they knew it was only a stray bullet.

Speculation centered upon a military shooting exercise as the culprit. The equestrian center, in the Deodoro section of Rio, is placed on a military base. Officials have not considered moving equestrian and other events to other locations.

“It’s too soon to regret or to think a different place could be better,” Andrada said. “This facility is the ideal facility for welcoming the horses. It’s the ideal facility for some of the sports we’re going to have here, like BMX. And obviously, we don’t think this incident is something that is part of the normalities.”

The bullet did no harm but landed in a crowded room, underscoring the anxiety of these games.

“It happens to have come through in the corner, and it happens to hit the ground where there isn’t anybody there,” Stroud said. “But stray rounds don’t have any say in where they land. It could have come through any of this roof, anywhere. At the very least it’s going to give you a nasty wound. You don’t need too much imagination to work out what one of the worst cases could be.”

After he saw the bullet sitting near him, Stroud continued about his day. He shot many pictures with one hand, using his other to speak with friends and reporters on his cell phone. He tugged on his tan photo vest and pulled open one of the many pockets.

“Maybe they could put some armored plates in these the next time around,” Stroud said.

Adam Kilgore in Rio de Janeiro contributed to this report.