This is the one situation where calling a tree company first is the wrong move. Here is the order to do things in.
1. Get everyone away from it
Treat every wire as live. All of them, including the one lying flat in the grass doing nothing, including one that has already sparked and stopped. A downed conductor can re-energize without warning when the utility runs an automatic reclose, and it can energize the ground around it — which is why you also stay away from puddles, fences, and anything metal near where it landed.
Stay back at least the length of the wire span, keep pets in, and do not let anyone walk under a limb that is holding a wire up in the air. If a wire is across a car with someone in it, the safest thing is for them to stay in the car until the utility arrives.
2. Call the electric utility, not us
The number is on your electric bill, and there is no charge for the call. Tell them a tree is on a line and give them the pole number if you can see one. This is not a courtesy call — until they cut power to that span, nobody can legally or safely work on the tree, and that includes us.
If there is any fire, or a wire is down across a road, call 911 as well.
3. Work out which wire it is
This determines whose problem the tree is, and it is worth knowing before you make any more calls.
The primary lines are the highest wires on the pole, running pole to pole down the street. Those are the utility's, always, and nobody but the utility touches a tree in them.
The service drop is the single cable that leaves the pole and runs to the side of your house. In most cases the utility owns it as far as the connection point at your house. A tree in the service drop is still a utility call first — but once the drop is disconnected or the power is cut, the tree itself is a normal tree job.
Everything past the meter — the mast, the weatherhead, the cable running down your wall — is generally the homeowner's, and that is often what actually gets damaged when a limb takes the drop out. If the mast is ripped off the side of the house, you will need an electrician before the utility will reconnect you.
4. Photograph everything before it is cleaned up
Once a crew arrives, the scene changes fast. Before that happens, take photos from several angles: the tree, what it landed on, the wire, the damage to the house or the car, and a wide shot showing the whole thing in context. Insurance claims go far more smoothly with those, and nobody ever regrets taking too many.
5. Then call a tree company
Once the line is dead or the utility has cleared out, the tree is just a tree — usually a badly stressed one that is partly on the ground, partly hung up, and holding a lot of stored energy in bent limbs. That is genuinely dangerous work and it is worth having someone do it who takes it apart in an order that makes sense rather than starting with the piece that looks easiest.
We will not put a saw anywhere near an energized line, and no outfit worth hiring will. If someone offers to, that is your answer about them.
What about the tree next door?
If your neighbour's tree came down on your line, it is still the utility's call for the wire, and the tree conversation is a separate one you will have to have with the neighbour and probably with both insurers. Take the photos anyway.
Short version: people first, utility second, photos third, tree company fourth. If you are somewhere in southeastern Massachusetts and you are at step four, call us.