Winnie Madikizela-Mandela arrived at Milpark hospital in Johannesburg on Thursday where her ex-husband, former president Nelson Mandela, is being treated.
Journalists and photographers surrounded her car as police and bodyguards tried to make room for her to get through.
One of Mandela's bodyguards came out and asked police to “clear this space for us for when we come out”.
There has been no word on the 92-year-old statesman's condition.
He was admitted to the hospital on Wednesday for what the Nelson Mandela Foundation called “routine tests”.
Media flocked to the hospital on Wednesday and many kept an overnight vigil. Scores of journalists continued to gather amid tight security on Thursday.
Children at McAuley House Primary School, neighbouring the hospital, shouted from classroom windows: “Get well Madiba, we love you Madiba.”
Mandela's personal assistant Zelda la Grange arrived at the hospital around 9am on Thursday. Photographers surrounded her car as she was ushered into the hospital by security guards.
Later, the daughter of Graca Machel, Mandela's wife, was seen driving into the hospital premises.
Police had tightened security at the hospital and kept out scores of journalists, photographers and cameramen, who were left to wait in the street leading up to the hospital. Traffic was backed up as officials searched vehicles for cameras.
Business Day reported his former personal assistant Jessie Duarte on Wednesday also visited the hospital.
CNN reported on Wednesday night that Mandela was flown from Cape Town to Milpark Hospital and brought to the hospital by military ambulance.
Hospital spokeswoman Erin Walsh would not comment.
“It is our policy to respect patients and we would not give any details about the admission to anyone expect the family,” she said.
The Foundation issued a brief statement just after 4pm on Wednesday reading: “We can confirm that Mr Mandela is at Milpark Hospital undergoing routine tests. He is in no danger and is in good spirits.”
There had been no further word from the Foundation by 11.15am on Thursday. - Sapa