Four-lepton production in proton–proton collisions, pp→(Z/γ⁎)(Z/γ⁎)→ℓ+ℓ−ℓ′+ℓ′− , where ℓ,ℓ′=e or μ , is studied at a center-of-mass energy of 13 TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 2.6 fb −1 . The ZZ production cross section, σ(pp→ZZ)=14.6−1.8+1.9(stat)−0.3+0.5(syst)±0.2(theo)±0.4(lumi)pb , is measured for events with two opposite-sign, same-flavor lepton pairs produced in the mass region 604 GeV for all opposite-sign, same-flavor lepton pairs. The results are in agreement with standard model predictions.