How can I get a summer internship during these times?

It depends on what type of internship you are looking for and where you are living. A lot of traditional internships are likely to be canceled this summer, as you mentioned. If you live in a part of the US that hasn't been hit as hard, there might be some opportunities close to home at local businesses.

There are alternatives to summer internships that could still help you explore your potential major and look good on college apps. Keep in mind that colleges are probably going to be super understanding that summer programs/internships aren't possible for many students. You might have to get creative to make the most of your time, and potentially prioritize personal and intellectual growth over "what looks good" ... even though I'd argue that personal growth DOES look good.

You could try online classes that are relevant to your potential major. Also, there might be volunteering opportunities that are relevant to your potential major (examples: If you're interested in science/medicine major, you could volunteer online with the Red Cross. If you're interested in education, you could tutor students online or younger family members or make a Youtube course of your own. If you're interested in political science, you could see if there are online volunteering opportunities for a local political campaign.)

If you're interested in computer science, take some coding classes online and build a project this summer. Honestly, I think colleges will be really understanding about what students do this summer. As long as you challenge yourself, either through courses, volunteering, internships, a part-time job, learning something new, focusing on a hobby, or caring for family during this hard time, that's what will make your application impressive. No matter what you do, stay healthy and safe!

have a look at roundpier, some online opportunities there...