The Connecticut Blood Center has issued an urgent call for blood donations ahead of the July Fourth weekend.

The center says the state is facing a critical blood shortage, specifically for O-negative and B-negative blood.

Officials say O-negative is especially important because it is the universal blood type and is used during emergencies when there is not enough time to determine a patient's blood type.

Donations are down 27% than what is needed to meet hospital demand. Donations often drop during the summer because of vacations, school breaks and people having busier schedules.

Connecticut Blood Center says summer is also known as "trauma season" because injuries and accidents increase as the days are longer and people participate in more outdoor activities.

Connecticut Blood Center is also calling on businesses, schools, religious groups and community organizations to host drives throughout the summer. They are reminding people that due to updated Food and Drug Administration guidance, more people are now eligible to give. People can donate blood every 56 days.

As a way to encourage donations, Connecticut Blood Center is offering donors either a branded T-shirt or a backpack at all drives from Friday through July 7.

Donors can book appointments online or by calling 800-688-0900.