Hawaii is seeing a spike in coronavirus cases, with 15 new infections reported Friday — the highest number since mid-April — bringing the statewide total to 706.

The surge in cases following Memorial Day and graduation gatherings is alarming, Lt. Gov. Josh Green told the Honolulu Star-Advertiser, adding that he is expecting another spike in the eight to 10 days after last weekend’s Black Lives Matter marches drew crowds of 10,000 protesters.

The 15 new cases were the most since April 18, when 21 new infections were reported.

“We’re right now witnessing the Memorial Day spike, which also coincided with graduation parties, so we have to be very careful,” Green said. “Ten of those cases are in one family (in Waipahu). This is the kind of thing that can happen — you get a spike and it’s a family cluster.

“That’s why we’re spending a lot of extra energy proposing standards which will require travelers from the mainland to get a test before coming to Hawaii. We will not be able to afford a large spike and have positive COVID-19 travelers to Hawaii at the same time. It underscores that we’re going to have to be super careful as we open up travel from anywhere.”

Gov. David Ige, who is expected to approve a plan for mass testing of all travelers to Hawaii, reassured the public at his daily COVID-19 briefing Friday that the state is prepared for an uptick in infections.

“This was expected as we began the phased process of reopening businesses and activities. I just want to assure everyone that it’s a manageable number that we have prepared for,” he said. “We still continue to have amongst the lowest numbers of new positive cases in the country and the lowest level of hospitalizations as well as mortality.”

State Health Director Bruce Anderson said there has been no direct evidence that mass gatherings in Hawaii are spreading COVID-19, although the rest of the country has seen an increase in associated cases.

“We aren’t seeing a lot of widespread illness. The cases we’re seeing are associated with known clusters of cases or other cases here on Oahu. We have the situation well under control,” Anderson said. “But it does point to the importance of keeping to the restrictions we have. There is still virus in our community. It is very infectious and we need to be sure we’re not letting up in our infection control measures.”

Hawaii health officials said the “family cluster” of 10 cases occurred in the same household. All the family members were previously in quarantine when one tested positive.

Three of the cases are in communities where health officials said they are “actively canvassing door to door to provide educational information and to offer testing.”

Anderson said the state is investigating a case at Maunalani Nursing and Rehabilitation Center, one of Hawaii’s largest nursing homes, but is confident the staff member hasn’t infected other employees or patients. Also, no transmission has been found in the cases of two employees at Kala­kaua Gardens who tested positive last week.

As of Friday, there were 62 active infections in Hawaii and a total of 627 patients now considered recovered since the start of the outbreak in February. The state’s coronavirus death toll remains unchanged at 17.

Meanwhile, the Department of Land and Natural Resources’ Division of Conservation and Resources Enforcement said it had received reports of a party this weekend at the Kaneohe Sandbar that was being promoted on social media.

“This is irresponsible and it’s potentially dangerous because of COVID-19 considerations. The postings are promoting illegal activity due to the number of people they suggest may be involved,” said DOCARE Chief Jason Redulla. “Oahu has seen a spike in coronavirus cases the last few days and health experts say precautions like social distancing and wearing masks while around others must continue to keep the infection curve flat. Encouraging others to gather in a party-like atmosphere, at a place that is limited in space, does not help the situation.”

Of the more than 58,579 coronavirus tests conducted by state and clinical laboratories, about 1.2% have been positive.

While Hawaii has seen an increase in daily cases in June, the low infection rate compared to the rest of the nation has intensified calls for Ige to reopen more of the state’s devastated economy, especially tourism. However, Ige extended this week the mandatory 14-day quarantine for trans-Pacific visitors until July 31.

“This is a marathon. As we begin to see increased activities throughout our community, as we reestablish interisland travel so that our families can reconnect with each other across the state, we certainly expect to see an increase in the number of COVID-19 (cases),” Ige said. “I want to assure you that our health care system is prepared. We are monitoring activities to ensure that the health and safety of our community continues to be a top priority.”