Four people in the same family have died from coronavirus in the US state of New Jersey, with three more relatives in hospital.

Grace Fusco, 73, and six of her adult children fell ill after attending a large family gathering.

Nearly 20 other relatives are now self-quarantining and waiting to find out if they have also been infected.

The death toll across the US has continued to rise, as experts warn against any kind of social gathering.

'Unbearable tragedy'

The four family members who died are Grace Fusco and her children Rita Fusco-Jackson, Carmine Fusco and Vincent Fusco.

Rita Fusco-Jackson, a Catholic school teacher, 55, died on Friday. She had no underlying health issues, according to state health commissioner Judith Persichilli.

New Jersey health officials said Ms Fusco-Jackson was the second person to die from Covid-19 in the state, and the first fatality had also recently attended a Fusco family gathering.

Carmine Fusco died on Wednesday, followed hours later by his mother, Grace Fusco.

According to the New York Times, Grace Fusco died without knowing that two of her children had already succumbed to the deadly respiratory illness sweeping the planet.

On Thursday, Vincent Fusco died in the same hospital where his mother had recently passed.

According to family member Paradiso Fodera, 19 family members who attended the same dinner are now self-isolating and have waited nearly a week to learn the results of their virus tests.

"Why don't the family members who are not hospitalised have the test results? This is a public health crisis," Ms Fodera told CNN.

She continued: "Why should athletes and celebrities without symptoms be given priority over a family that has been decimated by this virus?"

"This is an unbearable tragedy for the family."

A niece of Fusco-Jackson took to Facebook to grieve the sudden loss, NBC reported.

"My mom is one of 11, last Thursday I went to sleep having 10 aunts and uncles! Friday I woke up and found out I only had 9. Just a few minutes ago I found out I only have 8," she wrote.

"Please hold your love ones close and cherish every second and minute you have together."

'Stay at home'

More than 200 people have now died from Covid-19 in the US, with over 15,000 known infections and cases in all 50 states.

More and more US states and cities have begun lockdown procedures in an effort to prevent the rampant virus from overwhelming hospitals.

Testing in the US has lagged behind other industrialised nations, leading to questions about the actual spread of the infection in North America.