A New Zealand Olympic official barely missed being hit by a stray bullet at the equestrian center in Rio de Janeiro.

A bullet has narrowly missed a Kiwi official at Rio de Janeiro's Olympic equestrian centre, while a bomb squad blew up a bag near the road cycling finish line, amid heightened security fears on day one of the Games.

The bullet, believed to have been fired accidentally by a soldier, went through the room of a media tent at the venue and landed on the floor during the lunch break of the dressage event on Saturday (early Sunday NZ Time).

The venue is on a military base in the northern suburb of Deodoro, and the bullet was a military grade 5.56mm round.

ROB CARR/GETTY IMAGES A member of the Brazilian National Force holds the bullet shot into the media tent at the equestrian venue.

No one was hurt, but One News reported the bullet narrowly missed Kiwi press attaché Diana Dobson. It landed inches from one of the media tables at the end of the room where the press conferences are held, leaving a clear hole in the roof.

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ALEXANDER HASSENSTEIN/GETTY IMAGES Members of Rio de Janeiro's bomb squad carried out a controlled explosion in Copacabana.

New Zealand Olympic Committee communications manager Ashley Abbott said members of the New Zealand team at the venue were being contacted to inform them of the incident.

Eventers Shane Rose, Chris Burton, Sam Griffiths and Stuart Tinney were competing at the venue on Saturday.

Abbott said media had been advised by a police officer assigned to the team to gather in a workroom to await further advice.

ROB CARR / GETTY IMAGES The bullet sits inside the media centre.

In a later statement Abbott said it had executed its security protocol and team members were provided with immediate advice.

"The New Zealand police assessment is that the bullet was fired unintentionally rather than with intent."

"We have advised all team members to remain within the accredited areas at the venue and travel bubble to bubble. Team members should remain aware and exercise caution.

ROB CARR/GETTY IMAGES Venue operations staff look at the bullet hole.

"We are awaiting a final outcome to the investigation and continuing to remain in close contact with the appropriate authorities."

A Rio 2016 spokesman said: "We are aware of the incident and monitoring the investigation by the security forces. No one was hurt."

French Photographer Pierre Costababie was working nearby at the time.

ROB CARR/GETTY IMAGES The bullet went through the tent's roof.

"We heard a big noise like someone hit a hammer on iron and we all looked around and then we saw the bullet on the ground," Costababie told AAP.

"Then we noticed the hole in the roof ... It wasn't a loud bang because, from looking at it, I thought it was a long-range bullet fired from about two or three kilometres."

BLAST IN COPACABANA

ALEXANDER HASSENSTEIN/GETTY IMAGES The bomb squad near Copacabana Beach.

The shot was fired about the same time an explosion was heard at near the finish line of the cycling road race in Copacabana.

Kiwi George Bennett was taking part in the road race at the time.

Reporters could hear a loud boom on the press tribune and felt the ground shake as the cyclists had about 70 kilometres to go on Saturday.

A half dozen military police cordoned off the area. No one was immediately evacuated, and it did not appear that anyone was injured.

An Olympics spokesman assigned to the event said the blast was a controlled explosion of an unattended backpack.

Police say blast near Rio Olympics cycling course is controlled explosion of suspicious package pic.twitter.com/mdUd7dvypF — Team China (@XHSports) August 6, 2016

"The security services found a suspicious package close to the cycle road race finish line in Copacabana and as a precaution decided to perform a controlled explosion," the spokesman said.

"There is no impact to the race, which is ongoing."

The bag was found behind the grandstands at the end of the cycling road race along Copacabana Beach, where spectators had earlier gathered for the start of the event.

There were no signs of panic or injuries when the blast occurred, a witness said.

There had been several bomb scares in the city the last couple weeks.

A few blocks of the high end neighbourhood of Leblon were shut down two weeks ago when a doorman reported a suspicious package in front of a building.

A bomb squad came out and found that the sports bag only contained clothes.

MAN SHOT DEAD NEAR OPENING CEREMONY

On Friday night (Saturday morning, NZ time), spectators leaving the Olympic opening ceremony at Maracanã Stadium were confronted by the body of a man shot dead nearby.

Eyewitnesses said that blood pooled on the road as medics tended to the man next to an ambulance.

Loud gunshots were heard earlier in the night, forcing games volunteers and others leaving the ceremony to duck for cover behind cars.

A shooter was seen running from the scene and fleeing in a car close to a university parking lot.

Rio 2016 spokesman Mario Andrada said he did not have "any information on any shooting outside or close to the stadium last night".

- Stuff and agencies