SACRAMENTO (CBS13) — Sacramento County has seen the most cases of COVID-19 in the area. Now, it’s also seeing one of the biggest second spikes.

In Sacramento, you’ll see no shortage of “Congrats Grad” cards and “happy birthday” balloons. It’s a sign summer celebrations are in full force.

“I have a big birthday this year, so I was taking a cruise to Europe so those were smashed and now were just going to have a big black and white black-tie party,” said one shopper at Party City near Arden.

But community gatherings seem to be the problem according to local health officials, and the root of a spike of COVID-19 in the county.

“We do know where most of these cases came from. There are four different events: two birthday parties attended from people out of town who helped to bring the virus here, a funeral and a large church gathering,” said Dr. Peter Bielensen, Health Services Director in Sacramento County.

The county contact tracing team says there have been increased cases after families have gathered inside homes, which is in violation of state and county health orders.

READ: Health Officials Urge People Who Attended Large Gatherings, Like Protests, To Get A Coronavirus Test

In the past two weeks, Sacramento County has grown from nine hospitalizations and two ICU patients related to COVID-19 to 33 hospitalizations and 14 people in the ICU.

“Since early April, when we peaked at 76 and 27 hospitalizations and ICU visits, we went way down to that nine and two,” Dr Bielensen said.

There’s also been a change in the age-group of people getting sick. As of Wednesday, almost 50% of the current cases are skewing younger, between ages 18-49.

County health leaders say recent reopenings of restaurants, stores, and hair salons may have convinced people the virus risk has gone away and a sense that it’s “okay” to have birthday parties and gatherings inside. Now leaders say they want to limit those.

“We would consider pulling back on the restrictions,” said Dr. Bielensen.

The county is moving forward with Friday’s opening, but the state says it will now work with health officials on increased safety messaging.